Working Principle and Structural Characteristics

As mentioned in the “Overview”, the DVBS type Roetz water-ring vacuum pump unit is composed of one or two Roetz vacuum pumps and one screw vacuum pump connected in series. The specific structure is shown in the following figure. Among them, the screw pump is called the pre-stage pump, the Roetz vacuum pump directly connected to the suction system is called the main pump, and the Roetz vacuum pump connected to the pre-stage pump and the main pump is called the intermediate pump. Since the Roetz vacuum pump must start under a certain allowable inlet pressure, a pre-stage pump must be equipped at the outlet of the Roetz vacuum pump to pre-suction. For a three-stage unit, the pre-stage pump of the main pump is the intermediate pump, and the pre-stage pump of the intermediate pump is the screw vacuum pump. For a two-stage unit, the pre-stage pump of the main pump is the screw vacuum pump. The suction speed ratio between each stage of vacuum pumps (the suction speed ratio between the rear-stage pump and the pre-stage pump) should conform to a certain ratio. The insufficient pumping capacity of the pre-stage screw vacuum pump will cause the Roetz vacuum pump to overheat and overload.

Since the main pump and the pre-stage pump both adopt dry vacuum pumps, the JZJLG series Roetz screw dry pump vacuum unit has the following main characteristics:

l There is no oil in the pump chamber, which does not pollute the suction system and can achieve clean vacuum.

l There is no oil in the pump chamber, which makes it very easy to recover solvents.

l The Roetz pump chamber and the screw pump chamber are treated with anti-corrosion coatings, which can remove water vapor, solvent gases, and various corrosive media.

l No waste oil or wastewater is discharged during operation, and there is no pollution to the environment.

l The requirements for cooling water are relatively low. Ordinary circulating water can meet the requirements for cooling the pump, and the cooling water volume is relatively small.

This unit’s main pump adopts the DVS series Roetz vacuum pump independently developed by our company. In the process of removing a large amount of water vapor and various solvents, the pump oil is not prone to emulsification.

The pre-stage pump adopts the DVS series screw vacuum pump independently developed by our company. It operates stably and reliably. Due to the mechanical seal adopted between the pump chamber and the gear oil tank, it can still work stably without nitrogen gas protection.

Typical applications of the Rotax screw vacuum unit: 

The Rotz screw vacuum unit features high vacuum level, wide working vacuum range, high pumping efficiency, and the flow passage can be treated for anti-corrosion. It is a dry and oil-free vacuum acquisition equipment. It has a wide range of applications and can be widely used in various industries such as medicine, chemical engineering, aerospace, electronics, new energy, metallurgy, etc. It can also be used in vacuum impregnation and vacuum drying processes in the power industry, and is an ideal supporting vacuum equipment for vacuum smelting, vacuum heat treatment, vacuum filtration, space simulation experiments, etc. The unit is applicable to high-vacuum distillation, drying, dehydration and crystallization processes in the chemical and pharmaceutical industries, which contain a large amount of condensate steam and a small amount of dust. 

The general composition of the DVBS Rotz screw vacuum unit 

First or second-level Roots vacuum pump 

2. Pre-stage screw vacuum pump 

3. Vacuum pressure transmitter 

4. Check Valve 

5.  Enter the shut-off valve 

6. Cleaning Valve 

7. Cleaning valve 

8. Nitrogen purging device 

9. PLC Electrical Control Cabinet 

Optional system add-ons: 

Pre-cooling and buffer tank 

Pre-filtering vacuum filter 

Vacuum level control variable frequency regulation system 

Rozz pump bypass pipeline and valves 

Solvent cleaning tank 

Monitoring of cooling water temperature, pressure and flow rate 

Nitrogen purging flow rate and pressure monitoring 

Post-stage condensation recovery device

工作原理及结构特点    
       在“概述”中已提到DVBS型罗茨真空泵水环泵机组是由一台或二台罗茨真空泵与一台螺杆真空泵串联而成,具体结构如下图，其中螺杆泵叫前级泵，与被抽系统直接相连的罗茨真空泵叫主泵，与前级泵和主泵相连的罗茨真空泵叫中间泵。由于罗茨真空泵必须在一定允许的入口压力下才能启动，因而在罗茨真空泵出口处须配备前级泵作为预抽,对于三级机组而言,主泵的前级泵是中间泵，而中间泵的前级泵即为螺杆真空泵，对于二级机组而言，主泵的前级泵即为螺杆真空泵。各级真空泵之间的抽速比(后级泵与前级泵的抽速比)要符合一定比例，前级螺杆真空泵抽气能力的不足会使罗茨真空泵过热和过载。
　由于主泵及前级泵均采用了干式真空泵，因此JZJLG系列罗茨螺杆干泵真空机组具有以下主要特点：
l  泵腔内无油，对被抽系统无污染，可获得洁净真空。
l  泵腔内无油，非常容易实现对溶剂的回收。
l  罗茨泵泵腔，螺杆泵泵腔防腐涂层处理，可抽除水蒸汽、溶剂气体及多种腐蚀性介质。
l  因工作过程中无废油、废水的排放，对环境无污染。
l  对冷却水的要求较低，对于泵的冷却，普通的循环水即可满足要求，且冷却水量较小。
该机组主泵采用了本公司自行研发的DVS系列罗茨真空泵,在抽除大量水蒸汽及各类溶剂的工艺中泵油不易乳化。
前级泵采用了本公司自行研发的DVS系列螺杆真空泵，运行稳定可靠，由于在泵腔及齿轮油箱之间采用了机械密封，在不充入氮气保护的情况下仍然可以稳定工作。

罗茨螺杆真空机组典型应用：

罗茨螺杆真空机组属于真空度高，工作真空范围宽，抽气效率高，过流部分能进行防腐处理，属于干式无油真空获得设备。适用范围广，能广泛应用于医药、化工、航空航天、电子、新能源、冶金等各种行业中。也可用于电力行业的真空浸漆、真空干燥工艺中，还是真空冶炼、真空热处理、真空抽滤、空间模拟实验等工艺的理想配套真空设备。机组适用于化工、制药行业的高真空蒸馏、干燥、脱水结晶等含有大量冷凝蒸汽及少量粉尘的工艺场合中。

DVBS罗茨螺杆真空机组的一般组成

可选的系统附件:

* 前置冷凝器、缓冲罐

* 前置真空过滤器

* 真空度控制变频调节系统

* 罗茨泵旁通管道及阀门

* 溶剂清洗罐

* 冷却水温度、压力、流量监控

* 氮气吹扫流量、压力监控

* 后置冷凝回收装置