Hiroyuki FUJISAWA*
Tetsuya MATSUYAMA*
*
New Business Development Department, Business Development Division, Fluid Machinery and Systems Company
Sales of the process pump model UCWC for the refinery and petrochemical industry began in August 2019. This product, conforming to API685, the international standard for seal-less pumps, is highly reliable. In addition, taking advantage of the feature of complete non-leakage, the product is offered for a wide range of applications in the refinery and petrochemical industry markets, which mainly handle hazardous liquids (flammable and hazardous liquids), safely and environmental soundly contributing to economical plant operation.
Keywords:Canned motor pump, Complete non-leakage, Environmental loading reduction, Conforming to API685
In 2019, we developed the model UCWC process pump for the refinery and petrochemical industries with TEIKOKU ELECTRIC MFG. CO., LTD. (hereinafter referred to as Teikoku), and launched it onto the market (Fig. 1). Compared with the model UCW (conventional model), the model UCWC is completely leak-free without a sealing system using mechanical seals, which is a major differentiating factor.
The main feature of this product is that it combined canned motor with pump of model UCW, which has been widely used as a process pump for the refinery and petrochemical industries, to achieve complete leak-free operation. This eliminates the risk of liquid leakage and contributes to environmental loading reduction. In addition, this product has no exposed rotating parts, which provides a high level of safety. Furthermore, the product can reduce costs for plant construction because it has neither a sealing system, nor accessory piping. The user does not need to manage or replenish the intermediate liquid for mechanical seals, which contributes to economical plant operation.
In recent years, the global demand for petrochemical products has recovered from the decline in demand caused by the global economic slowdown in 2008 and 2012, and continues to increase. The demand is particularly prominent in the Chinese market, and the demand for API process pumps used in the manufacturing process of basic petrochemical products is expected to continue for the next several years. In addition to the model UCW pump that complies with API 610, the model UCWC canned motor pump that complies with API 685 will be launched in the market in the future so that it is possible to recommend the process pump with different features according to the user requirement.
This paper introduces the outline and the features of the canned motor pump model UCWC.
Fig. 1 Canned Motor Pump model UCWC
This product conforms to the API 685 standard for process pumps for the refinery and petrochemical industries.
Since this product does not have a shaft seal, it is suitable for handling liquids that must not leak, such as flammable liquids, toxic liquids, dangerous liquids, and liquid of high or low temperature that cause environmental pollution. In addition, accessory pipes and complicated sealing systems for shaft seals are no longer necessary. Accordingly, the risk of leakage is reduced. Furthermore, since the rotating part is not exposed, no caught-in prevention cover is necessary. Its motor is also equipped with a protection device to ensure good protection.
In recent years, because of the demand for safety and environmental loading reduction, the double mechanical seals for process pumps have become the mainstream, and many process pumps are equipped with a sealing system. Sealing systems are becoming more complicated in order to collect and detect leaks.
For model UCWC canned motor pump, the motor shaft also serves as the pump shaft, resulting in integral structure, which makes the pump smaller and lighter than conventional motor driven pumps. In addition, it has no mechanical seal or sealing system, which saves more space. Figure 2 compares typical models. Compared to the existing model, the new model is more compact, with a 70% reduction in installation area and a 90% reduction in installation volume.
Fig. 2 Comparison of pump sizes (typical models)
Since the pump and motor are integrated into a single unit, there is no need for shaft alignment and centering work at the site during plant construction, resulting in a shorter time from pump installation to operation. During periodic repair of the plant, this also contributes to shortening pump maintenance periods and reducing the risk of nonconformity caused by shaft alignment of the pump.
The specifications for the canned motor pump model UCWC are shown in Table 1.
Figures 3 and 4 show performance ranges at 50 Hz and 60 Hz.
| Model | UCWC | |
| Handling liquid | Petrochemical process fluid | |
| Design pressure | 4.0 MPa | |
| Handling liquid temperature | ‒100 to +450 °C | |
| Handling liquid temperature | 610 m3/h max. | |
| Structure | Casing | End top |
| Impeller | Closed | |
| Bearing | Sliding bearing (inside motor) | |
| Suction diameter | 40 to 200 mm | |
| Suction diameter | Casing | SCS14 |
| Casing | SCS14 | |
| Main wetted material | SUS316 | |
| Stator can | ALLOY-C276 | |
| Rotor can | SUS316L | |
| Bearing | Carbon graphite or high hardness carbon graphite |
|
| Sleeve / Collar | SUS316 + Stellite（Stellite is a trademark of Kennametal Inc.）or SUS316 + high hardness | |
| Motor frame | CS | |
| Material | Model | FA-V，RA，BA |
| Explosion class | ⅡB,ⅡC | |
| Phase / Pole | 3 / 2P | |
| Output | 120 kW max. | |
| Heat exchanger | Multitubular type | |
| Material | API685 | |
Fig. 3 Performance ranges（50 Hz）
Fig. 4 Performance ranges（60 Hz）
Figures 5 and 6 show the pump configuration and cross-sectional view, respectively. Table 2 shows the parts list. The model UCWC mainly consists of a casing, an impeller, an adapter, and a main shaft. Its pump and motor are integrated into a completely sealed pressure vessel. The main features are shown below.
(1) There is no coupling to transmit the motor torque to the impeller.
(2) Since it uses its own liquid to lubricate the bearings and cool the motor, neither lubricating oil, nor a motor cooling fan is required.
(3) In this model, the pump casing and the motor are connected by an adapter. Thus, various combinations of a casing and a motor are possible.
Fig. 5 Structural drawing
Fig. 6 Sectional view
Table 2 Parts list
The model UCWC canned motor pump has a back-pull-out structure that allows disassembly and inspection of the rotary parts without removing the casing from the suction and discharge pipes at the site.
In addition, the mounting dimensions of the piping, the connecting flange, and the hydro shape of the impeller are the same as those of the existing model UCW.
Figure 7 shows the outline of the installation of the model UCWC pump on the casing and common base of the model UCW pump. This product uses the same casing as the model UCW pump. Thus, the model UCW pump can be replaced with the model UCWC canned motor pump in a short time and at a relatively low cost, making it highly cost effective.
Fig. 7 Outline of replacement
Canned motors are often installed in places where there is a risk of ignition and explosion; therefore, the motor body and terminal box are explosion proof.
The stator and windings are enclosed in a hermetically sealed can, whose material is a non-magnetic, corrosion-resistant metal, to protect them from the pump handling liquid; the can is welded to the motor frame. Similarly, the rotor is enclosed in a hermetically sealed can of the same material used for the stator to protect it from the pump handling liquid; the can is welded to the main shaft.
There are three types of motors: FA-V type (basic type) (Fig. 8), RA type (reverse circulation type) (Fig. 9), and BA type (high temperature isolation type) (Fig. 10), which can be used according to the application.
The FA-V type (basic type) is the standard design for the model UCWC canned motor pump. The pump casing and the motor are connected by an adapter. The bearings are lubricated and the motor is cooled by the pump's own liquid, which passes through the shaft hole and returns to the casing from the rear of the motor.
The RA type (reverse circulation type) is suitable for handling a volatile liquid, such as liquefied gas and low boiling point liquid. The structure in which the circulating fluid returns to the suction tank after lubrication of the bearings and cooling of the motor prevents cavitation at the pump suction section. Typical pump handling liquids include chlorofluorocarbon and liquid ammonia.
The BA type (high temperature isolation type) is suitable for handling high-temperature liquids such as hot water or thermo oil. The high-temperature pump liquid section and the motor section are separated by the throttle part of the adapter, and the motor is cooled by the circulating liquid that passes through the cooler. Therefore, the motor is not affected by the pump fluid temperature, and pump liquids up to 450 ° C can be handled.
Fig. 8 FA-V type (basic type)
Fig. 9 RA type (reverse circulation type)
Fig. 10 BA type (high temperature isolation type)
In the case of the model UCWC canned motor pump, there is a risk that the rotor will contact the stator can when the bearing wear exceeds the limit, and, in some cases, the can will be broken, allowing liquid to enter the secondary side of the stator and damage the motor windings. For this reason, the model UCWC is equipped with an operation monitoring device that constantly monitors the radial wear of the bearing and detects the rotation direction of the motor for predictive maintenance.
This paper explains the features and product outline of the model UCWC canned motor pump, in which pump technologies and canned motor technologies of Ebara and Teikoku are merged. Ebara and Teikoku will improve their cooperative system and build a relationship that allows them to share not only product information, but also sales information, and continue to further their collaboration in a wide range of fields. Based on the technology and experience gained through this joint product development, we will continue to expand our product range and develop products that meet the needs of many users. Lastly, we would like to express our deep appreciation to all the people who have provided their cooperation in this development.
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