Single Loop Controllers

Continuous technology improvement is ongoing in the pulp & paper industry to obtain the best possible performance. The improved plant performance translates to the higher quality improvement and lower cost, and simultaneously environmental friendly plant operation.

Automated control of industrial boilers is an excellent application for YS1700 microprocessor-based loop controllers. These instruments can be programmed to perform the operations of plant master, boiler master, fuel and air control with oxygen trim and drum level/feedwater control.

The boiler combustion control system is designed to maintain a proper air/fuel mixture under varying load conditions and within safe limits. The system should provide nearly complete fuel combustion as efficiently as possible. Discussions here are limited to oil and/or natural gas fired industrial boilers. 

Are you in the dilemma of retraining your instrument technicians and engineers since Moore Products has discontinued the Moore 352B & 352E? Are the Moore 352PLUS™ or 353 really your only choices? We have a better solution for you. Yokogawa's new US1000 digital PID loop controller provides more bang for the buck.

Many industrial plants have embedded the PID controls for flow, temperature, pressure, level, etc. in PLC's on the plant floor. In the event of a PLC failure, the control to these critical loops may be lost. The US1000-11 may be configured to act as an automatic backup station and operator interface if PLC service has failed.

The US1000-11 Dual Loop Digital Indicating Controller can easily be implemented as a three element boiler drum level/feed water controller. Steam drum level control is necessary to add makeup water as steam is delivered into the header pipe. The level measurement and feed water flow input are the process variables (PV) for a cascade control strategy.

Chemical addition to a flowing liquid stream is an excellent control application for the US1000-00 Digital Loop Controller. In both water and waste water treatment, chlorine is added as a disinfectant. A residual chlorine analyzer provides the process variable to a closed loop PID controller.

The US1000-11 Digital Indicating Controller can be programmed to provide two functions, as a heat exchanger temperature controller and a BTU calculator. Why perform both functions? The temperature control is used to maintain a constant product temperature on the discharge side of the heat exchanger.

Yokogawa's US1000-11 Digital Indicating Controller is the newest member of the Measurement & Control Division family of industrial and process controllers. One application that can easily be implemented is a reactor cascade control, using product and steam jacket temperatures as the process variables (PV's).

Most SLPC and YS170 controllers in the field contain a custom program stored on an EPROM in the case of the SLPC and in NVRAM in the case of the YS170. When upgrading from an SLPC or YS170 to a YS1700, it is necessary to either rewrite the program in YS1700 language or convert the program from SLPC or YS170.

The power plant for a small town has a single, coal fired boiler controlled by Bailey SLC controllers. Concerned about support issues for the aging controllers, the power plant initiated a control upgrade project.

YS1000 Series instruments can accept ONE direct input when a signal conditioning option is specified. The direct input replaces one of the non-isolated 4 to 20mADC (using a 250Ω shunt resistor) or 1 to 5VDC inputs. YS1700 can accept five analog inputs. YS1500 can accept four and YS1310, YS1350, YS1360 can accept two analog inputs. In all cases, one input can be signal conditioned.

Both centrifigal and axial compressors cannot be allowed to operate below the surge limit of the operating conditions. The machinery may be exposed to excessive stress and vibration. If the discharge flow demand is less than the compressor surge limit, some of that flow must be vented or recycled to the inlet to stay above surge.

Both centrifigal and axial compressors cannot be allowed to operate below the surge limit of the operating conditions. The machinery may be exposed to excessive stress and vibration. If the discharge flow demand is less than the compressor surge limit, some of that flow must be vented or recycled to the inlet to stay above surge.

In process operations, there are instances where ratio control is required to maintain a consistent blend of two or more components. This control action is used in chemical, food & beverage, and pharmaceutical batching operations.

YS100 series instruments are stand alone devices that control or indicate process variables throughout a manufacturing plant. RS485 communications cards can be optionally provided to transfer data from each instrument digitally to a PC-based operators station. Below is a typical system configuration to transfer data bi-directionally through this communications bus.

Steam drum level control is necessary to add makeup water as steam is delivered into the header and to the associated process equipment. The system should control the drum level at a specific set point while compensating for varying steam demands and drum pressures. For a given volume of steam and blowdown leaving the steam drum, an equal amount of water should replace that inventory.

Yokogawa enjoyed strong sales of its line of YS80 instruments from their inception in 1980 to discontinuation in 2008. Thousands of the SLCD (single loop controller) and SLPC (programmable controller) where sold in the United States. As parts began to become scarce, the next generation of high-end controller was designed and released as the YS100 series.

In process control it is not uncommon for systems to be affected by dead times, due to material transfer times. This is evident typically in pipelines. A fluid of density ρ and flow rate w in a section of pipe A the length of d takes the amount of time τ = ρAd/w to cover the whole distance (see Figure 1).

The YSS1000 setting software (hereinafter referred to as the YSS1000) is package software to configure the functions of the YS1000 series (hereinafter referred to as the YS1000) devices. Writing and reading of parameters and user programs of the YS1000, and PID tuning and monitoring of user programs can be performed through the use of communication.