SAC gas-infrared point heating

Introduction

PINTSCH ABEN’s gas-infrared point heating system SAC is modular structured and powered by natural gas or propane. The main system components are locally controlled by a computer, installed at the station control room or operations centre. The remote control and monitoring of SAC installations is a variant of the renowned  PA Line control and monitoring software program which PINTSCH ABEN developed for the German DBAG to be used for electric point heating installations.

Most important system components are the main gas supply regulation cubicle with accompanying gas flow control cubicle and the ignition control cubicle. Both are connected to the controlling PC. A main gas supply regulation cubicle controls the main gas supply of an installation. Trackside mounted ignition control cubicles supply gas and electricity for the burnerpipes and monitor their operational status. A single ignition control cubicle controls burnerpipes, mounted within an area up to Ø300-Ø400 meters. PC, gas flow control cubicle and ignition control cubicle(s) are connected -one to another- by a data cable. The total number of ignition control cubicles that can be coupled is 20. The maximum allowable total length of the data cable is 20 km.

Dial or GSM modems report faults to the technical or operations centre at remote distance. From there you can also control and monitor the SAC system.

PA Line Software Package

PINTSCH ABEN specifically developed the sophisticated PA Line computer program for the remote control and monitoring of points heating installations. The program offers a wide range of different screen visualisations. Some of the integrated screens are: station selection main menu, diagnosis main menu with process diagram, reports/failures overview, gas consumption, control loop parameters and historical database. Using the station’s database you can create graphics of all the measured values.

The SAC diagnosis main menu informs you about the pre-set temperatures to switch-on/off heating and the actually measured ambient and rail temperatures. Icon symbols in a process diagram show the actual gas consumption and moisture detection. Switch-on/off temperatures for wet and dry frost conditions can be set to local weather conditions.

The reports/failures overview shows the actual operational status of the main system components. Shown are for example the operational status of main gas supply, burner pipes and signalised failures (e.g. communication error, failure gas supply etc.). You can freely configure the number of showed reports and faults to your preferences. PA Line  stores all failure reports in a database. From this database you can extract a list of failures over a specific period. The list specifies type of failure, date/time of failure report and date/time of failure confirmation.

PA Line shows the gas consumption for each ignition control unit. The program immediately signalises increase of gas consumption caused by a damaged gas infrastructure. Monitoring this way results in a highly reliable and safe installation. In standard setting PA Line alarms you when the gas flow will deviate more than 3% from the nominal gas consumption of the installation. The allowable %deviation can be set to your own preferences.

A very interesting feature of the PA Line program is the extensive possibility to select graphics from the integrated historical database. You can overlook over a day, week or month the measured ambient and rail temperatures, moisture detection and consumed gas per ignition control unit. It is easy to discover trends in the graphs: you will get a better understanding of the heating process characteristics and the local climatic conditions.

Main Gas Supply Regulation Cubicle & Gas Flow Control Cubicle

The main gas supply regulation cubicle is an important SAC safety device. In this metal cubicle a gas control pipe section is mounted which guards the main gas supply for the total installation. The required controlling electronics are mounted in a separate stainless steel or plastic gas flow control cubicle.

The electronic hardware in the gas flow control cubicle is connected to the local PC and the ignition control cubicle(s) and detects any leakage in the gas pipe structure of the  installation: temperature, volume and pressure of the main gas flow are permanently measured.

The main gas supply (natural gas, bottled propane or propane from a storage vessel) is connected to a number of gas measuring and controlling instruments: minimal and differential gas pressure switches or a gas volume measurement device, 2 pressure gauges, 2 solenoid shut-off valves and 3 manually operated shut-off valves (inlet, outlet and by-pass).

Ignition Control Cubicle

The ignition control cubicle supplies gas and electric power for the burnerpipes and accurately monitors their functionality. The cubicle is constructed from stainless steel or plastic and contains 2 sections: one for controlling electronics, the other for gas instruments. The control section is connected to the local PC, the gas flow control cubicle and the possible other ignition control cubicle(s) with a shielded data cable 4×0,8 mm.

The control section supplies the 42 VAC power, required for the ignition of burnerpipes. It also supplies the 42 VAC system power for the connected ignition control modules (ICM) and monitoring signals (12 and and 24VDC). The connected ambient-, rail temperature- and moisture sensors activate the system. The SAC processor circuit in the control section offers you 6 digital outputs to switch lamps, signals, horns, lightning etc. You can plug in your laptop to make local diagnostics on the system.

In the gas section, a number of gas controlling and regulating instruments are mounted (shut-off valve, gas filter, gas pressure reduce valve, pressure gauge and a solenoid valve).

With one ignition control cubicle, a maximum number of 32 ignition control modules (ICM) can be controlled. The ICM connection boxes are embedded along the track and are all -one to another- parallel connected to the ignition control cubicle by power cables 4×1,5 mm.

Ignition Control Module

The ignition control module or ICM is a connection box from galvanised carbon steel, embedded near the track. One ICM supplies gas and ignition current for maximum 8 burner pipes.

The box contains a cable junction box, a gas shut-off valve and a SAC ASK control box. The processor circuit in the SAC ASK control box detects any burner pipe failure and immediately sends an alarm signal to the ignition control cubicle.

Meteoscan Weatherstation

To each ignition control cubicle a weather station is connected. PINTSCH ABEN designed the METEOSCAN station specifically for railway applications. This high-duty weather station determines the switch-on moment of the SAC switchpoint heating installation using programmed conditions for it’s measured values.

It is possible to order the METEOSCAN as a sensor station or as autonomous functioning switching station. To obtain the highest possible level of functional availability and durability, the pillar-shaped housing is constructed in full stainless steel. The METEOSCAN is maximally protected against vandalism. The control unit (mounted in an IP65 box), temperature/humidity sensors and cable connections are all mounted inside the pillar.

The pyramid on top of the METEOSCAN holds 4 series-connected moisture sensors which are continuously electrically heated to enable detection of snow. Important advantage of the 4-directional detecting sensor head is the optimal detection of drifting snow caused by trains and heavy wind.

Burnerpipe

PINTSCH ABEN burnerpipes are attached to the outside of the rail with a number of mounting clamps. One clamp is fixed-mounted to the burnerpipe; the other clamps allow thermal expansion. The igniter, gas inlet and air intake are located at the same side of the burnerpipe. For a specific switchpoint, the required number of infrared gas burners depends on the radius/length of the switchpoint. For a 1:9 point 14 burners are required (18 for 1:15 points, 20 for 1:20 points). When 1 bar (Ga) propane or 0,5 bar (Ga) natural gas is used, a burnerpipe can be constructed with maximum 11 burners. The heating capacity of PINTSCH ABEN burnerpipes is approximately 1000 Watt/meter.

PINTSCH ABEN burnerpipes are constructed from a special designed square-shaped aluminium profile. Inside this profile there is a smaller – also square-shaped – ignition channel. A small part of the supplied gas flows from the main gas supply channel into the ignition channel via flame protection nozzles located between the burners. Flame protection nozzles are  important safety devices because they make it impossible that  fire passes over from the ignition channel to the main gas channel.

The igniter contains an electronic circuit that transforms the supplied 42V AC current into a 2-3 kV high-frequent, pulsating ignition spark. The igniter produces a spark every 14 seconds and contains an integrated thermo-couple. When passing trains or heavy winds should blow out the burners, the system  automatically keeps in operation: the fresh gas pushes the burned gas out of the ignition channel and the spark from the igniter ignites the burners again.

PINTSCH ABEN pays very much attention to safety aspects: the wind-tight wire mesh package in each burner contains 6 layers which ensure that fire can not spread to the main gas channel.

Each igniter contains a thermo-couple which is mounted in such  way that the heat of the first infrared burner is measured. The thermo-couple enables the connected control system to monitor the operational status of the burnerpipe.