Sinopival Triple Offset Butterfly Valve

Sinopival (www.sinopival-valve.com) professionally manufactures triple offset butterfly valve with patented design.Our valves rank No.1 in China by advanced design,reliable working performance and good looking appearance.It's widelyused in applications which have high request of on-off performance, industries like oil & energy,gas separation,power plants,etc.  

Advantages:

1-Long service life-100 thousand on-off times

2-Bi-directional sealing

3-Zero leakage

4-Good appearance

1-Name:triple offset butterfly valve

2-Standard:API609

3-Size:2"~64"

4-Pressure:150LB~900lb

5-Material:WCB,Cast Iron,Ductile Iron,CF8,CF8M,CF3.CF3M and special alloy

6-Connection:Flange,wafer,lug,BW

If you need more technical information, please contact our engineers at sales@sinopival-valve.com

Sinopival triple eccentric butterfly valve

 Double Eccentric Butterfly Valve & PSA(Pressure Swing Adsorption)

Reminding: Copyright Reserved By SINOPIVAL VALVE CO.,LTD.(www.sinopival-valve.com)

High performance butterfly valves,generally refers to double eccentric butterfly valve and triple eccentric butterfly valve,due to their excellent working performance and high sealing ability (compared with concentric butterfly valve) are widely used in petrochemical,power plants,metallurgy,civil heating fields.Eccentric butterfly valves have the good working performacne to meeting sever and strict requirements in many different industries.Today, we are going to introduce the application of eccentric butterfly valve in air separation for making oxygen,hydrogen,CO etc. At present,the mature air separation system is PSA(Pressure Swing Adsorption),it need certain number of programmed valves (valve parts usually double or triple eccentric butterfly valve) in its pipeline system to control and adjust the medium.

Sinopival double (and triple) eccentric butterfly valve are widely used in this kind of PSA system due to the valves' excellent features:

1-Long service life,on-off 1 million times

2-Super reliable sealing performance:bidirectional sealing zero bubble

3-Patented seat design

4-Vacuum servie ability

5-Both liminated seat and full metal seat avaialble

6-Available fully rated to Class 2500lb

7-Anti-blowout device design

8-Fire-safe design optional

9-Excellent flow and throttling characteristics covering services from cryogenic to high temperature

Following we are going to briefly introduce application of double (and triple) eccentric butterfly valve in PSA (VPSA) process for making oxygen gas

PSA(Pressure Swing Adsorption for Making Oxygen) Introduction

1. The Main Technologies and Comparison of Air Separation & Oxygen Making

Oxygen in industrial production and daily life has a wide range of uses, the air contains 21% (volume concentration) of oxygen, is the cheapest oxygen raw materials, so oxygen is generally obtained by air separation.

1.1  Technologies of Air Separation & Oxygen Making

1.1.1 Cryogenic separation process: it’s the traditional oxygen making technology, the oxygen made in this way has high purity, wide product variety and suitable for large-scale oxygen making.

1.1.2 Pressure swing adsorption process (PSA): it’s new oxygen making technology, featured with low investment, low energy consumption, suitable for low purity request, small & medium scale applications.

1.1.3 Membrane separation process: not yet mature and this kind of technology are not applied in industry and come into use.

1.2  PSA process features (compared with membrane separation process)

1.2.1 The PSA process is more simple and does not require complex pretreatment equipment.

1.2.2 Oxygen purity can reach up to 95%, nitrogen content less than 1%, the rest is argon.

1.2.3 Oxygen making scale smaller than 10000m³ / h, the consumption of electricity is lower, smaller investment;

1.2.4 High degree of automatic operation of the device, convenient to open and stop;

1.2.5 The equipment operation independence is strong, the security is high;

1.2.6 The device is simple, flexible operation (part of the load is superior, conversion speed of the load is faster);

1.2.7 Low operating and maintenance costs;

1.2.8 Low cost of civil works, occupy less land.

1.3 Comparison Between Pressure Swing Adsorption Separation Process and Membrane Separation Process (refer to following table 1)

Item	Membrane Separation Process	Pressure Swing Adsorption Separation Process
Separation Principle	Liquefied air, separate oxygen and nitrogen according to their different boiling point	Raise pressure and adsorption,vacuum pumping and desorption,adopt the different adsorbability of oxygen and nitrogen to achieve separation
Main Characteristics of Equipment	Complex technology process,more facilities required,including air compression system, air precooling system, air purification system, the expansion unit, heat exchange system and rectification tower etc	Simple process, less equipment, including blower ,vacuum pump and the adsorption tower, etc
Process Characteristics	Operated at -160～-190℃ cryogenic environment	Normal temperature operating
Operation Characteristics	Long start time, usually in 15 to 40 hours, must continuously operate, can not be intermittent operation,if a short shutdown, restart require long time.	Short start time,generally less than 30 min.,both works for continuous and intermittent running
Maintenance Characteristics	Complex facilities structure,high machining precision,big technical difficulty of maintenance,and high maintenance cost	Sinple facilities structure, small technical difficulty of maintenance,and low maintenance cost
Civil Works and Installation Characteristics	Occupy large land area, high requirement for factories and infrastructure, high project cost.Long installation cycle, big technical diffculty, high installation costs.	Occupy small land area, no special requirement for factories and infrastructure,low project cost.Short installation cycle, low installation costs
Oxygen-Making Cost	High electricity consumption for small& medium scale oxygen making,about 0.5～1.0KW/Nm3	Low electricity consumption,about0.32～0.35KW/Nm3
Safety	The equipment is regulated by the pressure vessel specification. Can cause local accumulation of hydrocarbons, there is the possibility of an explosion.	Low operating pressure, free from pressure vessel regulations, does not cause local accumulation of hydrocarbons

2. Principle of Pressure Swing Adsorption Separation for Making Oxygen 

2.1 Principle of pressure swing adsorption separation for making oxygen

The main components in the air are nitrogen and oxygen. By selecting the adsorbents that have different adsorption selectivities to nitrogen and oxygen, an appropriate process is designed to separate oxygen from nitrogen and obtain oxygen.

 Nitrogen and oxygen both have a quadrupole moment, but the quadrupole moment（0.31A \u65289X） of nitrogen is much larger than that （0.10 A\65289X）of oxygen, so the adsorption capacity of nitrogen on zeolite molecular sieve is stronger than that of oxygen (stronger acting force between nitrogen and molecular sieve surface, as shown in Chart 1 below).

Thus, under pressure status when the air is passing through the adsorbent bed containing the zeolite molecular sieve adsorbent, the nitrogen is adsorbed by the molecular sieve, while the oxygen is less adsorbed and enriched in the gas phase and flows out of the adsorbent bed to separate the oxygen gas and the nitrogen gas to obtain oxygen gas . When the molecular sieve adsorbs nitrogen to near saturation, shut down air flow and reduce the pressure of the adsorbent bed. The nitrogen adsorbed by the molecular sieve can be desorbed and the molecular sieve regenerated and reused. Two or more adsorbent beds to switch jobs, can continuously produce oxygen.

Argon and oxygen have close boiling point, the two are difficult to separate, them together in the gas phase to be enriched. Therefore, the pressure swing adsorption oxygen plant usually can only get 90% ~ 95% concentration of oxygen (oxygen up limit of 95.6%, the rest is the argon), compared with concentration of 99.5% obtained from membrane air separation unit , also called oxygen-rich.

2.2 Brief Facilities Introduction for Pressure Swing Adsorption Separation for Making Oxygen

From the above principle, it can be seen that the adsorbent bed of pressure swing adsorption air separation oxygen plant must contain at least two operation steps: adsorption and desorption. Thus, when there is only one adsorbent bed, the product oxygen is interrupted. In order to continuously obtain the product gas, usually two or more adsorbent beds are provided in the oxygen plant, and additional necessary steps are provided in view of energy saving and smooth operation.

Each adsorbent bed is typically subjected to repetitive steps of adsorption, forward depressurization, evacuation or depressurization regeneration, rinse displacement, and pressure equalization. At the same time, each adsorbent bed is in different operating steps, under the control of the computer time switch, so that several adsorption bed in coordination, at the pace of time are staggered, so that the pressure swing adsorption device can run smoothly, continuous obtain product gas.

According to the different methods of desorption, pressure swing adsorption oxygen is divided into two processes (see table 2 above):

   2.2.1 PSA process: under pressure adsorption (0.2 ~ 0.6MPa), atmospheric pressure desorption. Investment is small, simple equipment, but high energy consumption, suitable for small-scale oxygen-making applications.

2.2.2 VPSA process: atmospheric pressure or slightly higher than atmospheric pressure (0 ~ 50KPa) under the adsorption, vacuum desorption. Equipment is relatively complex, but the higher efficiency, lower energy consumption, suitable for large-scale occasions of oxygen-making.

Table 2 Comparison Between PSA and VPSA process

Technology Process	Suitable for Oxygen-making Sclae m3/h	Adsorption Pressure KPa	Desorption Pressure KPa	Concentration of Oxygen %	Electricity Consumption KWh/m3	Oxygen Rate %
PSA	≤200	200～600	大气压	80～93	0.7～2	30～45
VPSA	100～10000	0～50	－45～－80	80～95	0.3～0.5	46～68

For the actual separation process, other trace components in the air must also be taken into account. The adsorption capacity of carbon dioxide and water on conventional adsorbents is generally much greater than that of nitrogen and oxygen, and the adsorbent can be adsorbed and removed by the addition of a suitable adsorbent (or by the oxygen-making adsorbent itself). The number of adsorption towers required for the oxygen plant depends on the scale of the oxygen generation, the adsorbent performance and the process design, and the running stability of the multi-tower operation is relatively better, but the equipment investment is higher. The current trend is to using highly efficient oxygen adsorbents ,minimize the number of adsorption towers as less as possible, employing short operating cycles to improve plant efficiency and to save investment .

For More,Ask For High Performanc Butterfly Valve Catalog to Sinopival, or contact us at sales@sinopival-valve.com

Copyright ©2016 SINOPIVAL VALVE CO,LTD.,All Right Reserved.

Valve Dynamic Seal  and Static Seal

www.sinopival-valve.com for valve support

Valve sealing cannot be ignored and regarded as a important subject in valve applications , this is because most reasons of valve leakage phenomenon are related with it.Following is going to introduce them:

1. Dynamic Seal

Valve dynamic seal mainly means the stem seal,the key point to solve valve dynamic seal issues is making sure no medium leakage happens when valve stem do movements.

1.1 Packing Box Style

So far,the valve dynamic seal mainly basing on packing box, basic styles of packing box are:

1.1.1 Gland-stlye

This is the most used type and can be classified many styles, from compression bolt, there are T-shape bolt,double-end bolt and eyebolt; from gland, there are integral type and combined type.

1.1.2 Pressing nut style

Though the overall size f pressing nut is small, compressing force limited and subject to used be in small size vale.

1.2 Packing Features

The packing touch stem directly and fully filled in packing box, to prevent medium leaking.Packing need to have following characteristics:

1.2.1 Good sealing performance

1.2.2 Anti-corrosion

1.2.3 Small friction

1.2.4 applicable to medium pressure and temperature

1.3 Common Packing Materials

1.3.1 Flexible graphite

A new type of sealing material

1.3.2 Asbestos packing:

Good high-temperature resistance and anti-corrosion, but sealing effect is poor when used lonely, so always impregnated or attached to other materials.

1.3.3 Oil-soaked asbestos packing

Its basic structure in two forms, one is twisting style, the other is braided. And  also classified to round shape and square shape.

1.3.4 PTFE braided packing

This kind of packing has excellent corrosion resistance and can be used for cryogenic media.

13.5 Rubber O-ring

Its sealing effect is good when applied in low pressure situation. But working temperature is limited, such as natural rubber can only be used for 60 ℃.

1.3.6 Plastic molding packing

Generally made of three-piece, can also be made into other shapes. The plastic mostly adopt PTFE, but also use nylon 66 and nylon 1010.

1.3.7 Other packing form

Among 250 ℃ steam valves, if using asbestos packing and lead ring alternately as the packing, the leakage of steam will be reduced; some valves, the media often change, adopting asbestos packing and PTFE together as the apcking, sealing effect will be better. To reduce the friction on the stem, in ome occasions, you can add molybdenum disulfide (M0S2) or other lubricants.

1.3.8 Bellows seal

With the rapid development of the chemical industry and atomic energy industry, flammable, explosive, toxic and radioactive substances increased, more stringent requirements are exposed to the valve seal, and some occasions have been unable to use packing seal, thus resulting in a new seal type - bellows seal. This seal without packing, it is also called no-packing seal. Both ends of the bellows are welded to the other parts. When the stem lifts, the bellows telescopic, as long as the bellows itself does not leak, the media will not be able to leak. For insurance purposes, often using bellows and packing double seal.

2.Static Seal

A static seal usually refers to a seal between two stationary surfaces. The main method of static sealing is to use washer and gaskets.

2.1 Washer & Gasket Materials

2.1.1 Non-metallic gasket materials

Such as paper, hemp, leather, asbestos products, plastics, rubber and so on. However, material like paper, hemp, leather and the like, there are pores, easy to penetrate, when used to be impregnated with oil, wax or other impervious material. Rarely used in valves

2.1.1.1 Asbestos products and asbestos belt, rope, plate and asbestos rubber sheet. Asbestos rubber plate which has compact structure,good pressure temperature resistance performance, widely used in connection of valve-to valve and valve-to pipe.     

2.1.1.2 Plastic gaskets , have a good corrosion resistance and most widely used. Variety types like of polyethylene, polypropylene, soft PVC, Teflon, nylon 66, nylon 1010, and so on.

2.1.1.3 Rubber products have soft texture and a certain resistance ability of acid, alkali, oil, sea water. Types like natural rubber, styrene butadiene rubber, nitrile rubber, neoprene, isobutyl rubber, polyurethane rubber, fluorine rubber.

2.1.2 Metallic gasket materials

Generally speaking, metal materials, have high strength, high temperature resistance. However, lead is not the case, only to take its characteristics of resistant dilute sulfuric acid. Materials like brass, copper, aluminum, low carbon steel, stainless steel, monel alloy, silver, nickel and so on.

2.1.3 Composite gasket materials

Such as metal foreskin (internal asbestos) gaskets, combined wave washer, wound spiral gaskets and so on.

2.2 Performance of Gasket & Washer

As the case may be, the valve gasket frequently changes. Common gaskets are: rubber flat washers, rubber O-ring, plastic flat washers, PTFE gaskets, asbestos rubber gaskets, metal washers, metal shaped washers, metal foreskin washers, wave washers, wound spiral gaskets.

2.2.1 Rubber flat gasket & washer

Easy deformation and compression needs little force, but the pressure & temperature resistance ability are poor, only for low pressure & temperature application. Natural rubber has a certain acid and alkali resistance, working temperature should not exceed 60 ℃; neoprene is also resistant to certain acid and alkali, working temperature 80 ℃; nitrile rubber oil proof, working temperature 80 ℃; fluorine rubber has good corrosion resistance, temperature resistance performance better than the general rubber, can be used in the 150 ℃ medium.

 2.2.2 Rubber O-shaped gasket & washer

Its cross-section shape is round and has certain self-tightening effect, its sealing effect is better than the flat washer, with smaller compression force.

2.2.3 Plastic flat gasket & washer

The most prominent characteristic of plastic is good corrosion resistance, most of them with poor temperature resistance performance. PTFE ranking leading role among plastic ,not only excellent corrosion resistance, but also a relatively wide temperature range, range from -180 ℃ to +200 ℃.

2.2.4 PTFE wrapped gasket & washer

In order to make full use of  PTFE advantages while making up its shortcomings of poor flexibility,generally produce PTFE wrapped rubber or asbestos rubber gasket. In this way, it has same corrosion resistance as PTFE flat washer, but also good flexibility, enhance the sealing effect, reducing the compression force.

2.2.5 Asbestos rubber gasket & washer

It is made by cutting asbestos rubber sheet cut, having a good heat resistance, cold resistance, chemical stability, abundant supply and cheap. Its composition includes 60~80 % asbestos,10 ~ 20 % rubber, fillers, curing agents and so on. Asbestos rubber gaskets used, the clamping force should be too big. Because it can adhere to metal, so the better way is coating a layer of graphite powder on the surface, so as not to tear down strenuously.

Asbestos rubber sheet has four colors: gray, for low pressure (grade XB-200, pressure ≤ 16 kg / square centimeter, temperature 200 ℃); red for medium pressure (grade XB-350, 40Kg / cm2, temperature 350 ℃); purple, for high pressure (grade XB-450, pressure 100 kg / cm2 temperature 450 ℃); green for oil, pressure performance is also very good .

2.2.6 Metal flat gasket & washer

 Lead material, working temperature 100 ℃; aluminum 430 ℃; copper 315 ℃; low carbon steel 550 ℃; silver 650 ℃; nickel 810 ℃; monel nickel-copper 810 ℃, stainless steel 870 ℃.Among them, the lead with poor pressure resistance, , aluminum can be resistant to 64 kg / square centimeter, other materials can withstand high pressure.

2.2.7  Metal heteromorphosis gasket & washer

Lens washer: self-tightening effect, used in high-pressure valves.

Oval washers: belong to high-pressure self-tightening washers.

Tapered double gasket: for high pressure self-tighting seal.

In addition, there are other shapes, like square, diamond, triangle, tooth, dovetail, B-shaped, C-shaped, generally only used in high pressure valves.

2.2.8 Metal wrapped gasket & washer

Wrapping material are aluminum, copper, low carbon steel, stainless steel, Monel alloy. Inner filling materials are asbestos, PTFE, glass fiber. Metal has good temperature and pressure resistance properties, but also good flexibility.

2.2.9 Wave washer

Small compression force, good sealing effect. Often in the form of metal to non-metallic combination.

2.2.10  Spiral wound gaskets

It’s made of thin metal and non-metallic belt and tighten closly together, winding into a multi-layer circular, wave-shape cross-section, has good flexibility and sealing. Metal belt can be 08 steel, 0Cr13, 1Cr13, 2Cr13, 1Cr18Ni9Ti, copper, aluminum, titanium, Monel alloy production. Non-metallic materials are asbestos, PTFE and so on.

3.New Sealing Materials and Sealing Technology

3.1 Liquid seal

With the rapid development of polymer organic synthesis industry, in recent years there has been liquid sealant used in static sealing; this new technology, often called liquid seal. Liquid seal principle, is the use of liquid sealant adhesion, mobility and the effect of monomolecular film (the thinner membrane natural recovery tend to be greater), at the appropriate pressure, make it like a gasket to play the role. So the use of the sealant, also known as the liquid washer.

3.2 PTFE raw material seal

PTFE is a polymer organic compounds, before sintered into sealing products, called raw material. It’s soft and has monomolecular effect. The belt made of raw material called raw material belt, can be rolled and stored for long-term preservation. When come into use, forming freely, , as long as there is pressure, forming e evenly ring-shape film that has sealing function. As the gaskets of valve body and cover, no need to remove the disc or wedge, pry a gap, stuff the RM belt into the gap. Small compression force, not stick hand, nor stick flange surface, the replacement is very convenient, especially suitable for the tongue and groove flange.

3.3 Metal hollow O-ring

Good elasticity, small compression force,having self-tightening effect, a variety of metal materials available, which can be applicable from low temperature, high temperature and strong corrosive media can adapt

3.4 Graphite plate seal ring

In people's minds, graphite is brittle material, lack of flexibility and toughness, but after special treatment, it can be soft, have good elasticity. In this way, the heat resistance and chemical stability of graphite can be displayed in the gasket material. Moreover ,such gasket has samll compression force, the sealing effect is superior. Also can also made into belt combined with the metal belt, composed of excellent performance wound gasket.

Valve: Double offset butterfly valve

Valve: Double offset butterfly valve: Sinopival Double Offset Butterfly Valve Sinopival (www.sinopival-valve.com) professionally manufactures double offset butterfly valve wi...

Valve: Double offset butterfly valve

Valve: Double offset butterfly valve: Sinopival Double Offset Butterfly Valve Sinopival (www.sinopival-valve.com) professionally manufactures double offset butterfly valve wi...

Double offset butterfly valve

Sinopival Double Offset Butterfly Valve

Sinopival (www.sinopival-valve.com) professionally manufactures double offset butterfly valve with patented design.Our valves rank No.1 in China by advanced design,reliable working performance and good looking appearance.It's widelyused in applications which have high request of on-off performance, industries like oil & energy,gas separation,power plants,etc.  

Advantages:

1-Long service life-100 thousand on-off times

2-Bi-directional sealing

3-Zero leakage

4-Good appearance

1-Name:doouble offset butterfly valve

2-Standard:API609

3-Size:2"~64"

4-Pressure:150LB~300lb

5-Material:WCB,Cast Iron,Ductile Iron,CF8,CF8M,CF3.CF3M and special alloy

6-Connection:Flange,wafer,lug,BW

If you need more technical information, please contact our engineers at sales@sinopival-valve.com