10.1 Product Introduction

Shanghai Hanwei Special Valve Manufacturing Co. Ltd. specializes in manufacturing various kinds of special valves and is the sole famous producer manufacturing 24 way rotary valves.

The 24 way rotary valves is a high technology electro- mechanical product and is the key equipment in molecular sieve devaxing (LAB) units and paraxylene separation (Aromatics) units. Because of its complex techniques and manufacturing difficulty, there was only two manufacturers in the world who could produce this kind of valves and UOP monopolised the market for several ten years.

China Petrochemical (Group) Company gave the important state project, 24 Way Rotary Valve Research and Development, to Hanwei and Jinling Petrochemical Company Nanjing LAB Plant in order to apply the advanced simulating moving bed molecular sieve absorption separation process, decrease investment cost, improve enterprise benefits and petrochemical technology. Through expert's careful research, design, manufacture, and test, the rotary valve RVII was successfully developed in July 1998 and was installed in the newly built molecular sieve devaxing unit of Nanjing LAB Plant. After a long term of running, China Petrochemical (Group) Company convened an conference Authenticating Meeting on 24 Way Rotary Valve Research and Development. The leaders and experts attending the meeting gave much more praises in the rotary valve manufacture, technical level, quality, and running performance. This rotary valve can be commercially produced.

24 way valve covers a lot of technology such as mechanical science, electrical science, hydraulic science, and chemical process etc. Our company's engineers have took about 20 years to carefully research this kind of product. Hanwei has made lot of different size rotary valves for Yueyang Petrochemical General Plant (Parex) and Nanjing LAB Plant (Molex). After a long term of running, their performance are very good and don't have any faults. By now, for simulating moving bed molecular sieve absorption and separation process (Sorbex) its chemical process, key equipment (RV), molecular sieves, and catalysts can all be made in China.

This product has obtained the Chinese patent with patent no. ZL99240233.6

10.2 Application

The simulating moving bed process is an advanced chemical absorption separation process. When absorbents are put into the absorption tower, beds don't move and the rotary valve switches the inlets and outlets of each bed continuously at given interval. Therefore this process can not let the bed move and let the absorbent move between the beds depending to the rotary valve motion, so it is called a simulating moving bed process.

Therefore 24 rotary valves are mainly applied for simulating moving bed molecular sieve absorption separation process units in order to realize the continuous absorption separation and produce high purity products.

At present the molecular sieve absorption separation unit which adopt 24 way rotary valves and simulating moving bed mainly includes:

(1) Molecular sieve devaxing units: by using Molex process, paraffine is separated from camphorated oil or kerosene.

(2) Paraxylene units: by using Parex process, paraxylene is separated from C8 aromatic compounds.

Rotary valves can also be used in other absorption units such as Olex, Ebex, Cymex and so on.

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10.3 Structure and Function

The 24 way rotary valve can be divided into two sections, namely the main valve and hydraulic unit.

(1) Main valve

The main valve is the key body of the 24 way rotary valve, which realizes distributing several streams. The main valve comprises of the bottom head, rotor plate, seal plate, top head, drive mechanism, position indicator, valve position and zone signal feedback equipment, and cylinder working state signal feedback equipment. Refer to Fig. 1.

Bottom head
The bottom head can support all parts of the main valve. There is 7 stream pipes and 24 process pipes which are in connection with 24 beds of the absorption tower. It has very slick and smooth surface and has 7 concentric channels and 24 holes.

Rotor plate
The rotor plate is installed over the bottom head. There are 7 stream overcrass pipes which aim at the 24 holes of the bottom head. It also has a very click and smooth surface which fit with the seal plate.

Seal plate
The seal plate is non-metal anti-wear disc and is held tightly on the smooth surface of the rotor plate by screws and retainers. Therefore the streams in the 7 concentric channels cannot leak and ensure their sealing.

Top head
The top head is a cylinder type pressure container and is connected with the bottom head by flanges and studs which can contain valve trims like the rotor plate etc. The medium pressure in its cavity can press the seal plate on the bottom head tightly and ensure the required essential sealing pressure.

Driving mechanism
The driving mechanism comprises of the cylinder, ratchet wheel and pawl, upper drive shaft, lower drive shaft, aligning bearing, and mechanical seal. The cylinder is installed in the cover of the ratchet wheel above the top head. The hydraulic unit provides with pressurized oil and the oil supplies energy for the ratchet wheel and pawl.

The cylinder working state feedback equipment is installed on the retainers of the cylinder piston rod and comprises of 2 explosion-proof sensors which is used to send signals to the automatic control system. The upper drive shaft is connected with the ratchet wheel and the lower drive shaft connected with the rotor plate. The upper drive is connected with the lower drive shaft with a coupler. The above three connections become an transmission train, namely, the cylinder pushes the pawl, the pawl pushes the ratchet wheel, and the ratchet wheel makes the upper drive shaft, lower drive shaft and rotor plate step forward synchronously.

Position indicator
The position indicator comprises of an pointer and scale disc which is installed above the top head and gives 24 valve position indication. The pointer is installed in the upper part of the upper drive shaft and steps forward synchronously. The pointer can indicate the valve position and the stream entry position.

Valve position and zone signal feedback equipment
The valve position and zone signal feedback equipment is located on the top of the main valve and in a closed steel made cylinder. This unit sends 24 valve position signals and 7 zone signals to the automatic control system.

(2) Hydraulic unit

The hydraulic unit is a independent part of the 24 rotary valve, which supply enough pressurized and flow hydraulic oil for the drive mechanism of the main valve.

The hydraulic unit comprises of the oil tank, electric motors, filters, oil pumps, regulating valves, solenoid valves, accumulators, oil heaters, oil coolers, and oil tubes etc. The principle of the hydraulic unit refers to Figure 2.

The running reliability of the hydraulic unit is very important, therefore, this unit has double electric motors and pumps and can be switched automatically form each other when faults appears in one. In emergency, it can be operated by hand. Because of the pressure relief for electric motors and pressure hold for the cylinder, this methods can greatly extend its life, make its running stable, and make the noise low.

The electrical controller of the hydraulic unit is installed the electrical control box and can switch on or off the oil pump motor and fan motor, control the solenoid valves, and the operation station on site. This unit can output the working state signals of the hydraulic unit to the automatic control system and receives commands from the automatic control system.

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10.4 Principle

Principle 24 process pipes are connected with the 24 beds of the absorption tower correspondently and seven different streams can enter or go out from the 24 beds of the absorption tower through the bottom head channels of the 24 rotary valves and the overcrass pipes of the rotor plate.

When the hydraulic unit provide the pressurized oil to push the drive mechanism and make the rotor plate rotates step by step, the seven overcrass pipes of the rotor plate can distribute the steams and realize the advanced simulating moving bed absorption separation process.

In normal, the 24 way rotary valve receives the commands from the automatic control system and step forward continuously and feed back the 24 valve position signals, 7 zone signals, oil cylinder and hydraulic unit working state signals. In emergency, the hydraulic unit can be changed to be operated by hand by using the operation station on site.

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10.5 Main Technical Data

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10.6 Valve Model

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10.7 Supply Scope

For newly built or expansion projects, Hanwei can provide with the rotary valves, spare parts, special tools, technical data, and site services.

Rotary valve

A set of 24 way rotary valve including the main valve and the hydraulic unit.

Spare parts

For the several year maintenance of the rotary valve, Hanwei can also provide with the following necessary spare parts except for the a set of 24 rotary valves.

● Rotor plate assembly 1 set
● Sealing plate 1 piece
● Mechanical seal 1 set
● O type seal ring 1 group
● Gralic connector 24 pieces
● Metal sealing ring for Gralic 24 pieces
● Sensors 33 pieces
● Solenoid valve 1 piece

Special tool

The following are special tools for assemblies or disassemblies the rotary valves.
● Rotor plate positioning shaft 1 piece
● Guide shaft 1 pieces
● Screw hole guide stem 3 pieces
● Rotor plate observational stem 3 pieces
● Wretch 1 set

Technical data and documental package

● 24 way rotary valve catalogue 5 pieces
● Operation manual of 24 way rotary valve 5 pieces
● Asembly drawing of 24 way rotary valve 5 pieces
● Principle diagram of hydraulic system 5 pieces
●Performance parameters and operating instructions of important parts and electrical elements.
● Product quality documents

Services

● Help with product installation on site.
● Technical training for the operating or maintenance persons of the customers.

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10.8 Ordering Notification

The 24 way rotary valve is an specific unit designed for the specified absorption separation process. To ensure the 24 way rotary valve is in correspondence with the process type and parameters, customers shall provide with the following data when ordering.

● Absorption separation process type, for example Parex or Molex.

● 24 way valve size(valve code), for example, RVI, RVII, RVIII, RVIV.

● Capacity of the unit, its unit is Tons/Year

● Technical Data such as stream sorts, flow rate, pressure, temperature etc.

● Process flow block diagram.

● The bed numbers and positions in absorption zone, rectifying zone I, desorption zone, and rectifying zone.

☆ Note: The 24 way rotary valve excludes the automatic control system of the absorption separation unit. If customers require the automatic control system of the absorption separation unit (refers to Fig 4), Please clearly indicate. Its shall be given an separate quotation.

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10.9 Maintenance and Service

Hanwei can supply rotary valve parts or maintenance services for the 24 rotary valves in operation or the damaged rotary valves. These parts includes:

● Rotor plate assembly

● Sealing plate

● Mechanical seal

● Aligning bearing

● Oil cylinder

● O type seal ring

● Hydraulic unit

● Other rotary valve parts

● 24 way rotary valve repair or improvement

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