Boiler Optimization Test Trailer

In early April 1991, a very forward thinking electric utility approached us asking if we might have interest in developing a proposal to design and build an automated "boiler optimization test trailer".

On May 6, 1991 they issued the Purchase Order. On November 4, 1991 they took delivery of the unit and were testing with it one week later.

This view shows the Sample Analysis System portion of the trailer. The rack enclosures are mounted on vibrator isolators and house the analyzers, Fluke CPU, sample flow controls and digital panel meters.

PROBLEM:

Fuel is the single largest expense for a utility. Optimizing the use of it is critical to competing in the market. The utility had been contracting boiler optimization services from various regional testing companies. They believed that with the right automated equipment they could provide this service more accurately and less expensively "in house".

The system, however, was impossible to purchase as a package. Nothing like it existed on the market. Something like this could be engineered and specified into the ground (time consuming and expensive) AND they wanted delivery within six months, LESS, if possible.

The rear storage section is shown in this photo. Front to back on the left are the calibration gas rack, multi-drawer storage cabinet and technicians work bench. The rear doors of analyzer racks can be seen beyond the end of the work bench. The racked cal gas lines can be seen on the wall.

SOLUTION:

A mobile testing facility that met the expectations of everyone involved. It was an "operational tool" the first time it was used.

The only way delivery could be met was to design and construct the system almost "on the fly".

This system was designed and manufactured for the utility to be able to conduct timely and accurate testing of boiler optimization, air leakage, and the accuracy of automatic control systems. Initially, these tests applied to Boiler Optimization tests for gas-fired units and Air Leakage tests for coal-fired units. However, since its commissioning the system has performed all of its testing capabilities on both types of units. Prior to the advent of this system, the testing process was both labor and time intensive. The test equipment had to be calibrated and installed, the test had to be conducted, data recorded, analyzed and finally a report generated that would give operation personnel a direction for corrective action if any was indicated. Certainly all of these processes must still happen, but with this system they were able to reduce the time, labor units and capital required for the testing program and provide testing results (reports) prior to leaving the site.

This is the storage area for the solenoid enclosures, extender enclosures, bubbler arrays and the accessories for each of four sets that provide the 48 testing points. One of the empty sliding shelves can be seen in the lower left corner of this photo. The first device next to it is one of the solenoid enclosures. Next to it is one of the extender enclosures.

FEATURING: This system consists of the following five integrated sub-systems:

1. Trailer and Test Support
2. Sample Collection System
3. Sample Control and Analysis System
4. Calibration System
5. Data Acquisition System

The following is a brief description of each sub-system.

This photo was taken at our local ISA Exhibit. This is the technician work bench and storage unit area. A plug strip was provided for calibration equipment and other miscellaneous electrical needs. Plant instrument air can also be provided to this station via a quick connect at the trailer interface panel.

1. Trailer and Test Support

The system is contained in a 36’ 5th wheel trailer for storage and transport. The trailer is fully insulated and is fitted with two roof mounted HVAC units. The trailer is divided into three sections: the storage area, the testing area and the power distribution area.

One side of the storage area is fitted with shelving to store and secure for transport the system components that must be located remote from the trailer during testing. The solenoid and four extender enclosures (more of this in the sample collection system), being the heavier components, are stowed on special slide-out racks to reduce the chance of incorrect lifting injuries. On the opposite wall we provided custom racks for the necessary protocol calibration gases. Adjacent to the cal gas racks we located a multi-drawer storage cabinet for storing thermocouple wire, tools and accessories. A 5’ x 2’ workbench is provided for a technician work area.

The middle section contains the fixed testing equipment, a testing personnel work area and communications. More of this section is described in other sub-systems.

The front section contains the power distribution equipment and additional storage. It may be powered by 460 vac (welding outlet) or multiple (6) circuit 120 vac. Directly under this section a 460 vac receptacle is located. The vacuum pumps used to pull sample gases from the system being tested are also located in this area.

This is one of the four solenoid enclosures. They are insulated with polyurethane and freeze protected by a silicone strip heaters and thermostats. Note the guard on the end of the enclosure to prevent the quick disconnect couplings from damage during placement

2. Sample Collection System

The first element of this system is an adjustable probe. The probes have sample collection tubes and thermocouples (3 each).

From the probe assemblies the sample is routed through one of four unique 12 place bubbler arrays with individual flow adjustment designed specifically for use in this application. The sample is then sent to the solenoid enclosure.

From this solenoid enclosure a specific sample point is selected by the operation of any one of twelve solenoids in one of the four solenoid enclosures. An extender enclosure is positioned adjacent to the solenoid enclosure and the two are connected by multi-wire cables and keyed connectors providing control of the solenoids. These extenders also contain T/C inputs from the probe assemblies. The extender enclosures contain Fluke Helios units that are serially linked to the Fluke Helios CPU located in the trailer.

PC based software control emanating from the trailer then control the sequencing of the solenoid valves and polls the appropriate T/C for a particular point.

All sample lines, purge lines and the serial link are connected to the trailer at an interface panel. Keyed multi-pin weather tight connectors, T/C connectors and quick connect fittings were used throughout the system. All connectors, cabling and sample lines are either numbered or color coded to reduce errors during setup.

Some of the sample points are as far away from the trailer as 475 feet. To eliminate the need to "wait" for the sample we configured a solenoid array at the trailer that is controlled to provide "hot sample" from the next sample point while the current sample is being analyzed. This doubled the sample rate capability of the system.

This is a photo of one of the four extender enclosures. They are also insulated and heated. Above the Fluke unit is an opto-isolated array of relays that control the solenoids in adjacent enclosures. The serial link connectors are visible on the right.

3. Sample Control and Analysis

Before the samples are input into the individual analyzers, each sample is processed through a refrigerated dryer. The analyzer section of this facility is made up of Rosemount analyzers for O2, CO, NOX, CO2 and provisions for a future SO2 analyzer.

Each analyzer had different sample flow requirements. Annunciation and control was provided on a graphic replication of the system for "sample" flow, total "sample purge" (next sample) flow and "purge" flow as well as individual analyzer flow.

The trailer housing the system is a 36’, 5th wheel unit manufactured by Wells Cargo. Two roof mount HVAC units provide climate control for the analyzers and testing personnel. The unit is fully insulated. Convoluted noise suppression was added to the interior of the rear doors for noise abatement.

4. Calibration System

Regular calibrations are essential during testing to assure that the test instruments remain accurate and give valid data. The calibration system is a network of piping, solenoid valves, and regulators that allow the data acquisition system to run a calibration sequence in a semi-automatic mode. The rack in the rear of the trailer contains up to eight bottles of EPA Protocol calibration gasses to set the zero and span of each instrument.

Existing welding outlets were an obvious choice as a power supply for the trailer. A 100 foot cord fitted with 100 amp connectors was provided with the trailer. Also visible in this photo is one of the vacuum pump enclosures. The vacuum pumps were located here to reduce interior noise levels. Heat trace was installed on the interconnecting lines.

5. Data Acquisition System

The data acquisition system (DAS) consists of a Fluke Helios system complete with 1500 channel capability and samples at a rate of 60 channels per second. The Helios CPU communicates with the four extender boxes positioned on the economizer and air heater. The extender boxes act a nodes that allow communication to and from the 48 solenoids and thermocouples through on communication cable. The Fluke is linked to a PC running a CIM-PAC card and software. The DAS will automatically collect more than 67,000 data points and store them on hard disk into four separate report formats during a test. The system can produce an "as-found" report after the initial tests have been performed. This report can then indicate a direction for optimization efforts. After optimization, the testing can be repeated and an "as-left" report can be generated and left with the plant manager.

The DAS, as configured offers the flexibility to allow both the software and hardware to be re-configured to allow the system to support other types of plant tests.

Last modified: April 07, 2010

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