Safe & Reliable Solutions For The Oil & Gas Industry

Dpstar is the leading technology company that specializes in making industrial process control safer, more reliable and more efficient. Since the 90’s we have been dedicated to perfecting our core competence of innovating high-precision technology with low power consumption. This dedication continues to set new standards for products that communicate, monitor and connect our customers’ process measurement points to their process control systems. Our innovative, patented technologies are derived from our extensive R&D facilities and our thorough understanding of our customers’ needs and processes. Dpstar has a range of products that tick the boxes in these important areas. With over 30 years of experience of supplying signal conditioning devices, you can rely on us to quickly deliver products, supported with a 5 years guarantee, and a team of technically experienced staff ready to support you with free advice. We were one of the first companies in Malaysia to comply with the RoHS directive aiming to protect the environment. 

Signal conditioning devices protect signal transfer between field devices in safe areas and control systems by galvanic isolation of the loop. Particularly in case of long transmission paths, signal conditioners avoid compensating currents which may occur from ground loops. Signal conditioners also offer effective protection against electromagnetic disturbance or dangerous over voltages on the signal loops. Our range of signal conditioning devices is built to provide reliable, accurate, and flexible features with user-friendly interfaces. With ATEX and SIL approvals, PR has a portfolio of Intrinsically Safe products ready for use in the Hazardous Environments found throughout the Oil and Gas Industry. Other products also include pulse / frequency devices, limit switches, power supplies and devices for special functions. Discover what our know-how can do for your applications. 

Major Applications 

1. Crude tank
Level Measurement 

The crude tank contains unprocessed and unrefined crude oil. Level measurements are necessary to control the amount of oil in the tank and to prevent overflow. To measure the level, non-contact radar level sensors are used. Level sensors which come in contact with the crude oil can fail because crude oil can be very viscous, especially during cold winters. Furthermore, the contacting element often requires maintenance. The 9116B Is Universal Converter powers the two-wire style radar transmitter and isolates the signal, while the output is connected to the control system. The relay in the 9116B is configured as a window function alarm and provides an additional level of safety by switching if the tank level is unusually high or low. 

2. Heat Exchanger
Level Measurement

Prior to the distillation process, the crude oil is directed through heat exchanger units to preheat and thin the crude oil, making it ready for the for the next step in the process. Temperature measurements are necessary for efficient steam regulation through the primary side of the heat exchanger. This can be accomplished with the PR 5335D 2-wire transmitter with HART protocol. The 5335D is safely energized by the 9106B HART transparent repeater. Both the 5335D and the 9106B are IS & SIL 2 rated which was required by this application. 

3. Atmospheric Distillation
Temperature Measurement

rude oil travels from the primary heat exchanger to the atmospheric distillation unit, where it is separated into various “fractions” or “cuts”, such as fuel gases, LPG, naphtha, kerosene, diesel and fuel oil. A boiler heats and vaporizes crude oil at the bottom of the distillation column. The vapor moves upwards, cooling as it rises, which causes the heavier compounds in the vapor to condense back into a liquid. However, the lighter “fractions” of crude remain vaporized and continue moving upwards where they cool further and condense, one fraction at a time.  

Temperature measurements are necessary to monitor and control the temperature of the crude oil throughout the distillation column. Due to the high process temperatures, measurements are performed by TC-K sensors. The temperature measurements are converted using multiple PR 6337D HART double channel DIN-rail mounted temperature transmitters. Highly accurate CJC compensation is achieved using the dedicated 5910Ex/5913Ex CJC connector. The 6337D is mounted in the IS area in an UL approved cabinet. Each 6337D is powered from the safe area using the double channel 9106B. To reduce cabling, the 9106B transmitters are mounted on the PR power rail system where one 9410 power control unit provides 24 VDC to the power rail while enabling global monitoring of any device faults. 

4. Naphtha hydrotreater
Temperature measurement 

The naphtha cut from the atmospheric distillation unit is sent to the naphtha hydrotreater to remove sulfur and nitrogen compounds. The naphtha hydro treating unit uses a cobalt-molybdenum catalyst to remove sulfur by converting it to hydrogen sulfide that is removed along with unreacted hydrogen. Reactor conditions for a naphtha hydrotreater unit are around 400-500˚F (205-260˚C) with a pressure of 350-650 psi (25-45 bar). A two-wire style HART pressure transmitter is used to control the hydrotreater pressure. This application requires intrinsically safe signal measurement and SIL 2 with full assessment. The PR 9106B HART transparent repeater is connected to the pressure transmitter to bring the signal into the safe area. The output from the 9106B is connected to a control system and the HART information from the pressure transmitter passes through the 9106B for diagnostic purposes. 

5. Naphtha Reformer
Temperature Measurement  

The naphtha reformer unit is a primary process unit used to elevate gasoline octane and provide intermediate feedstock to BTX (Benzene, Toluene, Xylene) petrochemical processes. As this process provides higher octane material to the gasoline pool, both quality (octane) and reliability are key to ensuring gasoline blends meet the required specifications. Precise temperature measurements of all reactor heaters are necessary to ensure product quality. At the same time, it is essential to keep the reformer unit online as it provides hydrogen to units further downstream in the process. An unscheduled shutdown of the naphtha reformer can impact on other units that are dependent on the hydrogen generated. 

TC sensors are connected to the PR 5350B head mounted Profibus PA / Foundation Fieldbus transmitter for conversion to Foundation Fieldbus signals connected back to the control system. The 24-bit A/D converter assures the highest accuracy available in the process industry. Using a double element TC-sensor connection allows automatic switch to the second sensor if the primary sensors fails and a warning flag is transmitted over the digital signal. 

6. Aromatics extraction
Signal duplication / isolation

The aromatics extraction unit is used by refineries to separate a mixture of aromatics into pure benzene, toluene and mixed xylenes products. It is also commonly called a BTX (benzene-toluene-xylene) unit. The product streams are then either processed by a chemical unit within the refinery or sold to a nearby chemical plant. Solvent extraction in the aromatic’s extraction units has a low energy use compared to distillation. The most important function is to ensure product purity and at the same type minimize loss of products. To control the process, several gas chromatographs are needed. They provide positive identification of each chemical component and accurate measurement of the overall composition of chemicals in the mixture.  

Each process gas chromatograph provides an analog 4…20 mA signal that is re-transmitted to a chart-recorder for documentation and to the control system. The 9106B HART transparent repeater is the perfect solution, offering high accuracy and duplication of one 4…20 mA signal into two galvanically isolated 4…20 mA signals. The 9106 automatically provides a sinking or sourcing signal as needed to the downstream equipment… a feature unique to PR electronics. 

7. Isomerization Unit
Flow measurement 

The isomerization unit converts linear molecules to higher-octane branched molecules for blending into gasoline or feed to alkylation units. To ensure proper conditions inside the isomerization unit reactor, gas chromatographs are used to measure the product effluent leaving the conversion reactor. The active 4…20 mA signals from the sensors need to be connected to an active/sourcing PLC card in the safe area. The PR 9113B temperature / mA converter is the right fit for this task and by attaching the PR 4501 display / programming front to the 9113B, diagnostic capability is added to the application. 

8. Kerosene Hydrotreater
Temperature Measurement 

The kerosene hydrotreater unit is a catalytic chemical process unit used to remove sulfur (S) from kerosene. The purpose of removing the sulfur is to reduce the sulfur dioxide (SO2) emissions that result from using those fuels in automotive vehicles, aircraft, railroad locomotives, ships, gas or oil burning power plants, residential and industrial furnaces, and other forms of fuel combustion. Precise pressure and temperature control is needed to get the highest yield from the process. The output from both the pressure and the temperature transmitter must be available for two control systems. The pressure and temperature transmitters are both connected to one double channel PR 9106B HART transparent repeater. The 9106B inputs are wired so two independent active/passive outputs from each device are available – while maintaining SIL 2. 

9. Vacuum Distillation
Valve control 

As the name vacuum distillation (also referred to as “low temperature distillation”) implies, the distillation column is under a vacuum, or significantly less than an atmospheric pressure of 760 millimeters of mercury (mmHg). At low pressures, the boiling point of the ADU bottoms is low enough that lighter products can vaporize without cracking, or degrading, the oil. Vacuum distillation produces several types of gas oil. In the next stage of refining, these gas oils are further refined to make products such as light-cycle oil (a type of distillate), gasoline and naphtha. The vacuum column uses a series of pumps around the column to maintain temperature at the correct level at certain points along the tower to achieve the highest yield. The pumps are controlled by solenoid valves to prevent water waste when the pump motor is not working. To drive the solenoids, the PR 9203B solenoid / alarm driver is a great choice. The 9203B contains three built-in I.S. barriers, which makes it suitable for use with several coil types. Configuration and monitoring of the 9203 is done via the detachable display front (PR 4501) where it is also possible to select direct or inverted function. 

10. VGO & Resid Hydrotreater
Temperature measurement 

This process is the key to cost effective creation of Vacuum Gas Oil. The main goal is to prepare adequate feeds for further conversion units, generally FCC or hydrocracking, mainly by reducing sulfur and nitrogen contents to maximize propylene production. Maintaining tight temperature control is needed to obtain an efficient catalytic reaction. The temperature sensors connect directly to a cable, without using a transmitter housing. The long cables running back to the control system can pick up electrical noise and any measurement error can be increased further due to the formation of a ground loop. These problems can be solved using the PR 6337D (double channel) 2-wire HART transmitter. The TC mV signal is converted to a robust 4…20 mA signal close to the hydrotreater by mounting the 6337D transmitters in a UL cabinet approved for outdoor mounting. The 6337D provides high accuracy CJC compensation. Each 6337D is powered from the safe area using the 9106B HART transparent repeater, which also provides galvanic isolation. 

11. Fluid Catalytic Cracker 
Differential Pressure Measurement 

The fluid catalytic cracking unit is a process unit used to upgrade the heavier, higher-boiling fractions from the crude oil distillation by converting them into lighter, lower boiling, more valuable products. One main challenge for a fluid catalytic cracking unit is to avoid a catalyst reversal in the reactor-regenerator section. As the impulse lines for this application tend to plug, it is crucial that the differential pressure measurement works properly and detects line plugging quickly in order to avoid catalyst reversal. A redundant system with 2 differential pressure transmitters is required. Each transmitter is connected to the PR 9106B HART transparent repeater, the signal is split, one output is connected directly to the control system and the other is connected to an independent data logging system for documentation purposes. This solution detects line plugging and gives adequate time to act before a reversal of catalyst incident occurs. 

12. Alkylation
Flow Measurement 

The alkylation units are a sensitive but key process in many refineries. It’s a conversion process unit used to convert isobutene and low-molecular-weight alkenes into alkylate, which is a very high-octane component of the end-product gasoline or petrol. Sulfuric acid is used as a catalyst to produce alkylates out of hydrocarbons. ‘Fresh’ (high concentration) acid enters the process and is mixed with the hydrocarbons in a series of reactors and settlers. Measurement of the sulfuric acid concentration in the alkylation process is very important to ensure a high product quality. If the concentration is higher than required, acid consumption costs are too high. If the concentration is lower than required, the efficiency of the process is reduced. A Coriolis flowmeter is a great solution for getting the most accurate and reliable measurement of both mass flow rate and in-situ process density for this application. The analog output signal from the flowmeter is connected to an IS PR 9116B universal converter. The output from the 9116B (located in the safe area), is connected to the control system. In addition, the 9116B adds a relay alarm contact for sensor breakage detection. 

13. Heavy Oil Upgrading
Flow Measurement 

The coking process is devised to improve liquid yield and to reduce coke and hydrocarbon gas yields. A process for upgrading petroleum residuums by hydrogen diluent donor visbreaking employs coking of a higher boiling fraction of the visbreaker effluent wherein the hydrogen donor is also supplied to the coker feed either by excess feed to the visbreaker or by mixing a portion with the coker feed. Controlling the quantity of hydrogen donor in the visbreaker and coker feed proportionally controls the quantity of coke produced. Several of the processes in the coker require precise valve control, e.g. the feed valve which feeds the bottom product from the vacuum tower to the coker fractionator. It requires large flow passages due to potential particulate and must be able to handle high temperatures. Swings in control can cause upsets to the coker heater feed and the coker heater fuel requirements. This an intrinsically safety application where the valve is controlled by the PR 9107B HART transparent driver connected to an analog output on the control system. This solution provides high isolation and ultra-fast response time. 

14. Hydrocracker
Signal Repetition / Isolation 

The hydrocracker consists of four giant reactors. Inside the reactors the heavy waxy feed is broken down or cracked to produce petrol, kerosene and diesel components. The hydrocracker uses large quantities of hydrogen from the hydrogen manufacturing unit. The gas is boosted to 150 bar pressure by huge gas compressors. The presence of moisture in gas streams containing trace amounts of hydrogen sulfide produces corrosive byproducts. Such byproducts can destroy expensive process pipes and fittings. Therefore, it is very important to measure the exact moisture level to be able to maintain it in the optimum range from 20 to 30 ppmv. That can be done very precisely using a laser-based analyzer like the GE Panametrics Aurora Moisture Analyzer. 3 analog signals monitoring the gas quality from the moisture analyzer need to be connected to the control system in the safe area. To maintain the highest accuracy when repeating the 4…20 mA signal the 9106B HART transparent repeater is a great solution, providing high isolation, robust EMC performance, and process monitoring via the 4501 display/ programming front.

15. Diesel Hydrotreater
Temperature measurement 

Diesel fuels contain significant quantities of cracked stocks, such as FCC light cycle oil (LCO), which contains a large concentration of aromatic sulfur compounds. The effective removal of these species are done in the diesel hydrotreater, which requires tailored catalysts and process conditions, including consideration of the feed nitrogen content and aromatics equilibrium. Maximum reactor outlet temperature at end-of-cycle catalyst conditions is generally set at 725…750°F to avoid aromatics saturation equilibrium constraints. Reactor space velocity, hydrogen gas quantity and hydrogen partial pressure and reactor temperature are the variables that are optimized during the process design. The highest level of accuracy and stability is required. For temperature, a type N thermocouple is linearized, isolated and converted to a standard 4…20 mA signal using the PR 5337D (HART 5/7) temperature transmitters. The 4…20 mA signal from a hydrogen pressure transmitter must also be measured and excited. The double channel 9106B HART transparent repeater safely excites and measures both signals from the 5337 temperature transmitter and the hydrogen pressure transmitter, providing isolation, fast response time and the IS barrier to the safe area. 

16. Gasoline Hydrotreater
Flow Measurement 

The gasoline hydrotreater unit is a catalytic chemical process unit used to remove sulfur (S) from gasoline. The purpose of removing the sulfur is to reduce the sulfur dioxide (SO2) emissions that result from using the gasoline, while maintaining the octave value. Measurements of impurity and monitoring of the finished petroleum product stream exiting the bottom of the stripper are needed. A gas chromatograph sensor is used to measure the impurities in the hydrogen recycle stream and a second gas chromatograph sensor is used to monitor the finished petroleum product stream. Each of the sensors are connected to a PR 9116B universal converter to convert the active 4…20 mA signal into a 0…10 VDC signal for the control system. In addition, the PR 9116B adds relay monitoring of the input signal for error detection. 

17. Storage Tanks
Level Measurement 

The storage tanks contain all the end-products. Radar transmitters are used to perform the needed high accuracy level measurement in all the tanks. 2-wire radar transmitters perform high accuracy level measurements in all the tanks. The radar transmitters are powered and the signal re-transmitted using the 9106B HART transparent repeater with double channels. The outputs from all the 9106B devices are connected to the control system. 

Dpstar Group
No 35, Jalan OP ½, Pusat Perdagangan One Puchong,
Off Jalan Puchong, 47160 Puchong,
Selangor Darul Ehsan, Malaysia.
Email: [email protected]