Optimize Chemical Process with Signal Conditioning Devices

Dpstar providing signal conditioning (interface) devices for the process industry within temperature, I.S. interfaces, panel meters, signal isolators and converters. Dpstar is driven by engineers deeply committed to delivering leading-edge process instrumentation products. With our innovative and patented technologies, we take signal conditioning to the next level. All our products comply with or surpass the highest industry standards and ensure superior performance. Our daily contact with customers ensures that we have our finger on the pulse of the wide range of industries relying on chemical processes in their production. With our 30 years of experience our signal conditioning devices are tailor-made to suit the needs of the industries. Reliability, flexibility and user-friendliness are the key words in our product range, and on the market, we are known for our outstanding signal conditioning devices at attractive prices. Our product range is tailor-made for the numerous signals type used in industrial processes and the varied demands regarding supply voltage, communications protocols and special functions. We have the devices you can rely on even in tough operational environments with electrical noise, vibrations, temperature fluctuations etc. 

Signal conditioning is a set of operations performed on a signal that makes it suitable for interfacing with other devices or systems. Signal conditioners are the actual devices that perform this operation. These devices have an input and an output. The signal conditioning process is also known as a transfer function because the final effect is to convert an input signal (or measurement) into a suitable output signal. Signal conditioning in the chemical industry is largely a matter of reducing process costs as many chemicals require special manufacturing processes where every drop count. Accuracy, long term stability and response time have been optimized to the limits of current technology. Discover what our know-how can do for your applications. 

Major Applications 

1. Intake
Isolation / Conversion

Cellulose containing raw material is delivered to the plant in containers. The material is screened and a fan blows the material to the silo. Precise measurement of the fan speed is needed to prevent clogging of the conveying pipes. A speed sensor mounted on the fan is connected and powered by a PR 5223A programmable f/I converter, isolating the 0…15 KHz sensor signal and converting it to a 0…10 VDC signal for the PLC. 

2. Feed/Storage Silo
Level Measurement

Measurement of the level in the silo is needed to prevent overfilling the tank. A double system is being used with a radar transmitter mounted in the top of the tank and a pressure transmitter mounted on the side of the tank. Both transmitters are 4…20 mA two-wire units. The transmitters have to be powered and the 4…20 mA signal converted to 0…10 VDC for connecting to an AI card on the PLC. A perfect solution with very high accuracy and fast response time is using two 6 mm slim line PR 3104 isolated converters. 

3. Steaming & Impregnation
Temperature Measurement

Steam is used to preheat the cellulose material and remove trapped air. Dilute acid such as sulphuric acid is added. Precise temperature measurement is needed to ensure the right steam temperature in the process. This is accomplished using a compact high accuracy model PR 5337A hockey-puck style temperature transmitter mounted in a temperature sensor. The 5337A is powered by a PR 4116 universal converter which also converts the 4…20 mA signal to a 0…10 VDC signal for the PLC. 

4. Pretreatment Hemicellulose
Linearization / Conversion

Pretreatment is the first step of the cellulosic bioethanol process. The purpose of pretreatment is to make the cellulose more susceptible to being broken down so that it is ready for the enzyme hydrolysis step. Pretreatment hemicellulose, which is built up of various mono sugars with five or six carbon atoms, is leached out at low pH at a temperature > 170°C. Two continuous reactors are operating in series. When running two-stage dilute acid hydrolysis the first reactor is used for hemicellulose hydrolysis and the cellulose is decomposed in the second reactor at elevated temperatures > 200°C. Accurate pH measurement and control is needed in both processes to provide the highest yield. Both pH sensors are connected to a PR 5116A programmable transmitter, which linearizes the mV output signal from the pH sensor and converts the measurement to a 0…10 VDC signal for a PLC. 

5. Neutralization / Inhibitor Control
Temperature Measurement  

The slurry from the pre-treatment is neutralized and can also be treated to control inhibitors which can interfere with the fermentation process. High temperature is used in these systems, making the overall process more eco-friendly and increasing yield. Temperature measurement is done with fast reacting TC-sensors and the PR 5337A HART 5/7 transmitter which provides precise CJC compensation, isolation and conversion to a noise-robust 4…20 mA signal. The 5337 is powered by a PR 4116 universal transmitter which also converts the 4…20 mA signal to a 0…10 VDC signal for the PLC. 

6. Hydrolysis / Fermentation
Linearization / Isolation

The pre-treated material is fed to temperature-controlled tanks for enzymatic hydrolysis of the cellulose to mono sugars. The fermentation of sugars to ethanol starts when yeast is added. If the yeast is added together with enzymes, the process is named SSF (Simultaneous Saccharification and Fermentation). Alternatively, the hydrolysis and fermentation can occur in separate steps, SHF (Separate Hydrolysis and Fermentation). The solid residue remaining after hydrolysis and fermentation is mainly composed of lignin. The enzymatic hydrolysis typically happens at pH 4.5-5. Accurate pH measurement is therefore required to optimize the process. The pH sensor is connected to a PR 5116A programmable transmitter which provides linearization / isolation and a 0…10 VDC signal to the PLC. The two alarm contacts in the 5116 are also connected to the PLC, providing high & low pH alarm. 

7. Yeast Propagation
Temperature Measurement 

Yeast propagation is performed when non-commercial yeast is used. Propagation is made in three consecutive steps during several days. During propagation, temperature is maintained at a set level and the propagating yeast is aerated according to the particular strains requirement, so defined temperature control is needed. A good solution is using a sanitary temperature sensor with a PR 5331A temperature transmitter mounted in the sensor head. The output from the 5331 needs to be split into a 0…10 VDC signal for the PLC and a 0…20 mA signal for a data-logger. A great solution is the PR 3109 isolated converter / splitter. The 3109 powers the 5331 transmitter and outputs the two isolated analog signals with super-fast response time. 

8. Distillation
Temperature Measurement 

The ethanol created from the fermentation is heated, causing ethanol vapor to rise up a distillation column. Water condenses out from the vapor and the liquid flows back down, increasing the concentration of ethanol in the rising vapor. The ethanol rich vapor leaving the top of the column is cooled and condensed while the residue at the bottom of the column, the stillage, is sent to liquid/solids separation. Multiple Pt100 temperature sensors in the distillation column are required for accurate temperature control of the process. These sensors must be connected to the PLC, which only accepts 0…10 VDC inputs. All PT100 temperature wires are pulled to a stainless-steel control cabinet mounted at the bottom of the column. A compact and superior solution when it comes to accuracy and fast response time is using the galvanically isolated PR 3337 loop-powered HART 7 temperature converters. One multi-conductor cable for all the 4…20 mA signals is pulled back to the control room where a number of PR 3104 isolated converters handle powering of the 3337 transmitters, provide isolation and convert the 4…20 mA signal to the 0…10 VDC signal required by the PLC. 

9. Product Tank
Level Measurement 

The ethanol from the distillation process contains about 90% ethanol. The ethanol product is stored in a tank before being shipped from the plant. A pressure transmitter is used to sense the tank level in order to prevent overflow. For safety reasons, two pressure transmitters are mounted at different locations on the storage tank. Each 4…20 mA two-wire style pressure transmitter is connected to a PR 5714 programmable LED indicator, which powers, isolates, and re-transmits the signal. The displays are mounted in a stainless-steel control cabinet close to the product tank for convenient local readout and retransmission of the 4…20 mA signal for the control system. 

10. Membrane Filter Press
Signal Conversion

The fine particle solid residue is separated from the distillation stillage by filtration and used as fuel for energy production or as substrate for development activities in higher value applications. The process water is sent to the biogas plant at the industrial site. All process water streams from the plant are treated biologically before being discharged. DP transmitters are used to measure the pressure difference across the membrane filter press, assuring the highest system stability. Each DP transmitter is energized by the PR 4114 universal transmitter with the PR 4501 display / programming front attached. The 4114 also converts the DP signal to a 0…10 VDC signal, which is required by the PLC. This solution provides easy process calibration via the push buttons on the 4501 detachable programming unit. 

11. Discharge Pipes
Isolation / Conversion 

Precise flow measurements are needed from both the ethanol and water pipes. This task is solved using 2 two-wire styled flow transmitters. Signal isolation and conversion is needed for connecting the 4…20 mA signal to a PLC with a standard 0…10 VDC AI card. The perfect choice, which adds robust EMC protection and local diagnostics, is two of the PR 4104 Universal uni-/bipolar signal transmitter. 

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