The Design Principle of Segment Disc Control Valves

Figure 1.

The central throttle device of this control valve is two discs with segmented openings which slide on one another and seal against each other (Fig. 1). The segment discs are positioned vertically in the valve housing, facing the direction of flow. A moving disc is placed upon a rotationally fixed segment disc, the geometry of which determines the throughput capacity and characteristic curve. These two discs have the same number of segments and the moving disc is rotated via a push rod which is tangentially inserted. Consequently, the cross-section surface of the free segment passage changes when a control intervention is made.

Irrespective of the pending pressure differential, the moving segment disc is pressed onto the fixed disc via a spring pack- age. This ensures that the direction of flow is variable and that the valve can be installed in any desired location. Due to the fact that there are no metal seats with ring-shaped contact surfaces, no grooves will occur which can rapidly lead to leaks in traditional steam valves. Leakage ratios amounting to < 0.001% of the K_vs value are constantly achieved with the significantly less vulnerable surface seal.

Extremely robust segment disc valve from
Schubert & Salzer for steam distribution.

Thanks to this special design, segment disc valves are one of the few valves that are able to combine control precision and a high level of tightness, even in extreme conditions and which also experience hardly any wear.

The standard segment disc valves are available in finely graduated intervals of between DN 25 and DN 300 – and go up to DN 800 where necessary – in an intermediate flange design for nominal pressures up to PN 25. They can be used for media temperatures ranging between -60°C and +220°C (higher temperatures and nominal pressures are available on request). The robust valves have a rangeability of 60:1.

For more information, contact Miller Energy, Inc. by calling 800-631-5454, or visit their web site at https://millerenergy.com.

How to Change Loss of Signal Failure Mode on the Cashco Ranger Control Valve

This video provides step-by-step instructions on how to change the Cashco Ranger (control valve) loss of signal failure mode from air to open / fail closed to air to close/ fail open, as well as remounting and recalibrating the valve positioner.

The Cashco Ranger is one of the most popular control valves on the market. It is the most versatile, adaptable, and easily maintainable valve ever produced.

The Ranger offers over 6 different trim combinations. Trim can easily be changed in less than 5 minutes without disturbing the packing, actuator, or positioner calibration. The service area is a thread-less design, which resists corrosion or collection of chemical deposits.

A selection of 3 body materials with a broad temperature range from -325°F to +750°F makes the Ranger adaptable for use in steam, heat transfer fluids, slurries, gases, liquids, and cryogenic applications. The Ranger’s unique dual seating design provides both Class VI and backup Class IV seat leakage. And the standard patented live-loaded packing system lets you check and adjust packing without the need for specialized tools or complicated procedures.

For more information about Cashco in Metro New York, New Jersey, and Eastern Pennsylvania contact:

Miller Energy, Inc.
New York Metro and Northern NJ: 800-631-5454
Eastern PA, Southern NJ, Delaware: 888-631-5454
https://www.millerenergy.com

Happy Independence Day from Miller Energy, Inc.

New Hacking Risk for US Power Grids and Oil & Gas Industries

A report released in June, from the security firm Dragos, describes a worrisome development by a hacker group named, “Xenotime” and at least two dangerous oil and gas intrusions and ongoing reconnaissance on United States power grids.

Multiple ICS (Industrial Control Sectors) sectors now face the XENOTIME threat; this means individual verticals – such as oil and gas, manufacturing, or electric – cannot ignore threats to other ICS entities because they are not specifically targeted.

The Dragos researchers have termed this threat proliferation as the world’s most dangerous cyberthreat since an event in 2017 where Xenotime had caused a serious operational outage at a crucial site in the Middle East.

The fact that concerns cybersecurity experts the most is that this hacking attack was a malware that chose to target the facility safety processes (SIS – safety instrumentation system).

For example, when temperatures in a reactor increase to an unsafe level, an SIS will automatically start a cooling process or immediately close a valve to prevent a safety accident. The SIS safety stems are both hardware and software that combine to protect facilities from life threatening accidents.

At this point, no one is sure who is behind Xenotime. Russia has been connected to one of the critical infrastructure attacks in the Ukraine.  That attack was viewed to be the first hacker related power grid outage.

This is a “Cause for Concern” post that was published by Dragos on June 14, 2019.

“While none of the electric utility targeting events has resulted in a known, successful intrusion into victim organizations to date, the persistent attempts, and expansion in scope is cause for definite concern. XENOTIME has successfully compromised several oil and gas environments which demonstrates its ability to do so in other verticals. Specifically, XENOTIME remains one of only four threats (along with ELECTRUM, Sandworm, and the entities responsible for Stuxnet) to execute a deliberate disruptive or destructive attack.

XENOTIME is the only known entity to specifically target safety instrumented systems (SIS) for disruptive or destructive purposes. Electric utility environments are significantly different from oil and gas operations in several aspects, but electric operations still have safety and protection equipment that could be targeted with similar tradecraft. XENOTIME expressing consistent, direct interest in electric utility operations is a cause for deep concern given this adversary’s willingness to compromise process safety – and thus integrity – to fulfill its mission.

XENOTIME’s expansion to another industry vertical is emblematic of an increasingly hostile industrial threat landscape. Most observed XENOTIME activity focuses on initial information gathering and access operations necessary for follow-on ICS intrusion operations. As seen in long-running state-sponsored intrusions into US, UK, and other electric infrastructure, entities are increasingly interested in the fundamentals of ICS operations and displaying all the hallmarks associated with information and access acquisition necessary to conduct future attacks. While Dragos sees no evidence at this time indicating that XENOTIME (or any other activity group, such as ELECTRUM or ALLANITE) is capable of executing a prolonged disruptive or destructive event on electric utility operations, observed activity strongly signals adversary interest in meeting the prerequisites for doing so.”

Refractometry in Oil Refining and the Petrochemical Industry: Sulfuric Acid Alkylation

SULFURIC ACID, H₂SO₄

Typical end products

• Alkylate (premium higher-octane gasoline blending stock for motor fuel and aviation gasoline).

Chemical curve: Sulfuric acid 88-100 R.I. per Conc wt.-% at Ref. Temp. of 20 ̊C

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DOWNLOAD THE PDF VERSION OF THIS APPLICATION NOTE
FROM THE MILLER ENERGY WEB SITE HERE

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Introduction

Motor fuel alkylation using sulfuric acid (H2SO4) or liquid hydrofluoric acid (HF) is one of the oldest catalytic processes used in petroleum refining. The purpose of the alkylation is to improve motor and aviation gasoline properties (higher octane) with up to 90 % lower emissions compared to conventional fuel usage.

The problem with HF is that the catalyst forms a hazardous air pollutant when released as a superheated liquid, while H2SO4 does not. Therefore nearly 90 % of all alky units built since 1990 have adopted the H2SO4 technology. 

The leading alkylation unit licensor, with a 90 % share of the market, is DuPont (Stratco®). Another licensor is EMRE (Exxon Mobile Research Engineering, formerly K.W. Kellogg).

Application

In the process, isobutane is alkylated with low molecular weight olefins (propylene, butylene and pentylene) in the presence of a strong acid catalyst to form alkylate (the premium higher-octane gasoline blending stock). The catalyst (sulfuric acid) allows the two-phase reaction to be carried out at moderate temperatures. The phases separate spontaneously, so the acid phase is vigorously mixed with the hydrocarbon phase to form higher molecular weight isoparaffinic compounds.

After the reactor, the mixture enters a separation vessel where the acid and hydrocarbon separate. The acid is then recycled back to the reactor.

Instrumentation and installation

The K-Patents Process Refractometer PR-43-GP is installed after the settlers to continuously monitor in real-time the concentration of acid in the process.

The concentration of sulfuric acid is critical to achieve the complete consumption of isobutane. A highly variable concentration of isobutane in the feedstock upsets the sulfuric acid content in the process.

It is important to determine the proper quantity of acid that will be fed into the process. This is achieved by combining routine sample titration analysis with continuous acid monitoring by the K-Patents Process Refractometer. Real-time measurements reduce the need for sampling and laboratory analyses that cause delay in the implementation of any necessary adjustments to the acid flow.

Continuous monitoring removes the uncertainty involved between titration measurements. The K-Patents refractometer will indicate any gradual fluctuations in the acid flow, allowing precise control over efficient acid consumption and resulting in cost savings. It is also useful in preventing acid runaway, an unwanted situation commonly described as wild acid.

Acid runaway may happen when the acid strength drops below 85-87 % H2SO4. As a result, the reactions between olefins and isobutane turn into reactions of olefins only, producing polymers known as acid sludge, ASO or red oil.

The K-Patents refractometer is not affected by acid soluble oil (ASO). The refractometer indicates actual acid strength regardless of the amount of hydrocarbons present, which is essential when transferring acid emulsion. It is also an extremely useful tool in real-time process acid strength measurement during agitated conditions.

The initial acid concentration is typically 85-100 % and the temperature is 15 °C (59 °F). The benefits of the K-Patents refractometer’s continuous monitoring system include substantial cost savings due to reduced acid consumption, and smooth alkylate production without acid runaways.

The K-Patents Process Refractometer System for Alkylation Acid Measurement Consists of:

1. The K-Patents Process Refractometer PR-43 for hazardous locations in Zone 2. or The K-Patents PR-43 Intrinsically Safe model for installations in hazardous locations up to Zone 0.
2. Optional parts:
   1. Different flow cell options for easy sensor installation
   2. EXd enclosure for easy isolator and transmitter mounting
   3. Parts for a start up
   4. Spare parts supplied for two years of operation
   5. Start-up and commissioning service
3. User specified tests and documentation.

Alloy C-276/ASTM C276 should be considered as wetted parts material when the acid piping flow velocity is at a maximum of 6 m/s (20 ft/s). Alloy 20 can be considered when acid piping flow velocity is at a maximum of 1.8 m/s (6 ft/s). However, it is the responsibility of the end-user to specify the appropriate material, ensuring that it is satisfactory for the intended operating requirements.

Non-sparking incentive (Ex nA) and intrinsic safety (Ex ia) approvals are available for hazardous area installations.

Always consult an applications expert with any process-critical instrumentation application. By doing so, you will ensure a successful, safe, and efficient deployment.

Miller Energy, Inc.
https://millerenergy.com
800-631-5454

Reprinted with permission from K-Patents.

Hazardous Areas: Division and Zone Classification System

Hazards areas are associated with flammable
vapors or gases, ignitable fibers, and combustible dusts.

Hazardous areas refer to locations with a possible risk of explosion or fire due to dangerous atmosphere. The hazards can be associated with flammable vapors or gases, ignitable fibers, and combustible dusts.

Different hazardous area classifications exist in the North America and Europe. Generally, the National Electric Code (NEC) classifications govern hazardous areas in the US. While in Europe, hazardous area classification has been specified by the International Electrotechnical Commission (IEC).

Below is a description of the Division and Zone classification system.

CLASS	NATURE OF HAZARDOUS MATERIAL
CLASS I	Hazardous area due the presence of flammable vapors or gases in sufficient quantities to produce ignitable mixtures and cause an explosion. Examples include natural gas and liquified petroleum.
CLASS II	Hazardous area due the presence of conductive or combustible dusts in sufficient quantities to produce ignitable mixtures and cause an explosion. Examples include aluminum and magnesium powders.
CLASS III	Hazardous area due the presence of flammable fibers or other flying debris that collect around lighting fixtures, machinery, and other areas in sufficient quantities to produce ignitable mixtures and cause an explosion. Examples include sawdust and flyings

Division groups hazardous areas based on the chances of an explosion due to the presence of flammable materials in the area.

DIVISION	LIKELIHOOD OF HAZARDOUS MATERIAL
DIVISION 1	Areas where there is a high chance of an explosion due to hazardous material that is present periodically, intermittently, or continuously under normal operation.
DIVISION 2	Areas where there is a low chance of an explosion under normal operation.

Group categorizes areas based on the type of flammable or ignitable materials in the environment. As per NEC guidelines, Groups A to D classify gasses while Groups E to G classify dust and flying debris.

GROUP	TYPE OF HAZARDOUS MATERIAL IN THE AREA
GROUP A	Acetylene.
GROUP B	Area contains flammable gas, liquid, or liquid produced vapor with any of the following characteristics: Minimum Ignition Current (MIC) value equal to or less than 0.40 Maximum Experimental Safe Gap (MESG) value equal to or less than 0.45 mm Combustible gas with more than 30 percent volume Examples include hydrogen, ethylene oxide, acrolein, propylene oxide.
GROUP C	Area contains flammable gas, liquid, or liquid produced vapor with any of the following characteristics: Minimum Ignition Current (MIC) value between 0.40 and 0.80 Maximum Experimental Safe Gap (MESG) value greater than 0.75 mm Examples include carbon monoxide, hydrogen sulphide, ether, cyclopropane, morphline, acetaldehyde, isoprene, and ethylene.
GROUP D	Area contains flammable gas, liquid, or liquid produced vapor with any of the following characteristics: Minimum Ignition Current (MIC) value greater than 0.80 Maximum Experimental Safe Gap (MESG) value greater than 0.75 mm Examples include ammonia, gasoline, butane, benzene, hexane, ethanol, methane, methanol, natural gas, propane, naphtha, and vinyl chloride.
GROUP E	Area contains metal dusts such as magnesium, aluminum, chromium, bronze, titanium, zinc, and other combustible dusts whose abrasiveness, size, and conductivity present a hazard.
GROUP F	Area contains carbonaceous dusts such as charcoal, coal black, carbon black, coke dusts and others that present an explosion hazard.
GROUP G	Area contains combustible dusts not classified in Groups E and F. Examples include starch, grain, flour, wood, plastic, sugar, and chemicals.

NOTE: This post serves only as a guide to acquaint the reader with hazardous area classifications in the USA. It is imperative to discuss your instrumentation, valve, or process equipment requirement with a qualified applications expert prior to installing any electrical device inside of any hazardous area.

Understanding How Magnetic Flowmeters Work and the Difference between AC and DC Excitation

The electromagnetic flowmeter, commonly known as the "magmeter", gets its name from the magnetic field generated within the float tube that produces a signal proportional to flow. This principle employs Faraday's Law of Electromagnetic Induction. Magnetic flowmeters are built so the direction of the magnetic field is perpendicular to the flow and the line between the electrodes is also perpendicular to the flow. As a conductive liquid flows through the flowtube, an electro-motive force is generated. The electrodes detect the electro-motive force. The electro-motive force is proportional to the flow velocity, flux density, and the meter inner diameter. The flux density of the magnetic field and the meters inner diameter are constant values, therefore the magnetic flow meter can calculate the flow velocity and volumetric flow from the electro-motive force.

The basic components of the magnetic flow meter body are:

1. A lined flowtube (typically Teflon)
2. Excitation coils
3. Two electrodes mounted opposite of each other within the flowtube.

Current is applied to the coils in the magmeter to generate a magnetic field within the flow tube. As a conductive fluid flows through the meter, an electro-motive force is generated. This force is detected by the electrodes and the resulting value is converted to flowrate.

For more information on magnetic flowmeters, contact Miller Energy, Inc. by calling 800-631-5454 or by visiting https://millerenergy.com.