BOILEFF Raising the efficiency of boiler installations · 2014. 8. 11. · BOILEFF Measurement...

Project No. EIE/06/134/sI2.448721

BOILEFF Raising the efficiency of boiler installations

Deliverable 4.1: Summary report on the measurement concept

of boiler efficiencies

Start date of project: 01.02.2007 Duration: 32 months

Organisation name of lead contractor for this deliverable: INNOTERM Ltd. - Hungary

Dissemination level PU Public X CO Confidential, only for members of the consortium (includ-

ing the Commission Services)

BOILEFF Measurement concept of boiler efficiency

Table of contents

1 Introduction ............................................................................................................. 1

2 Conditions and basics of measurement concept ................................................. 2

2.1 Summary of EN 15378.......................................................................................... 2 2.2 Basics of applied measurement concept........................................................... 3

3 Measurement concept in detail .............................................................................. 4

3.1 Dependence from firing system.......................................................................... 4 3.2 Fuel consumption measurement ........................................................................ 5 3.2.1 Natural gas ............................................................................................................. 5 3.2.2 LPG......................................................................................................................... 5 3.2.3 Fuel oil .................................................................................................................... 5 3.2.4 Solid fuel ................................................................................................................. 5 3.3 Useful heat measurement.................................................................................... 6 3.4 Measurement of electricity consumption .......................................................... 9 3.5 Specification of equipments.............................................................................. 10 3.5.1 Fuel meter............................................................................................................. 10 3.5.2 Heat meter ............................................................................................................ 10 3.5.3 Electricity meter .................................................................................................... 10

4 Meter installation terms, instructions to installers..............................................11

4.1 Heat meter installation ....................................................................................... 11 4.2 Fuel meter installation ....................................................................................... 11 4.3 Electricity meter installation.............................................................................. 11

5 References ..............................................................................................................12

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1 Introduction

The objective of BOILEFF project is to improve the quality of boiler installations by developing a qual-

ity declaration and a performance declaration evaluated by a field test in each participating countries.

Work package 4 delivers the detailed concept for approach Guaranteed Performance Quality (GPQU).

On transferring elements of Energy Performance Contracting to the field of boiler efficiency, the WP

consists among others the following issues:

• development of technical concepts for the measurement of boiler efficiency suitable for guarantee;

This sub-task delivers the concepts for the measuring programs that need to be implemented in order

to be able to ensure the traceability of boiler efficiency. Measuring boiler efficiency has to settle par-

ticularly the following issues:

• suitable size of the measured boiler: We expect, that it is not possible to offer a metering program

to all kind of boilers.

On meetings partners were agreed to investigate boilers having power from 10 kW up to 70 kW

• suitable metering value: It needs to be clarified, if the annual energy use efficiency is the best

and/or only value to describe the quality of a boiler installation in a quantitative way. In this context the

potential of supporting measurements, that gives indirect information about the quality of boiler instal-

lation, will be discussed in detail. One of these values is the number and duration of heating cycles,

which can be delivers useful information about the efficient operation of the boiler. A tool to document

the actual characteristics of heating cycles could be used also in GPQU approach.

• description of specific requirements for the installation of the meters: There are various possibili-

ties for the placement meters, all of which produce different consequences for the kind of efficiency

that is actually measured.

• measurement of energy input to the boiler: So far, there are only few boilers on the market, which

are measuring the energy input. For all the other boilers a common system to calculate the energy

input in the boiler needs to be prepared. The system has to include different energy carriers, at least

the following ones: gas and oil. Solid fuel fired systems, which means generally wood or wood-pellet

as renewable energy resource, does not belongs to the scope of the project, as agreed by all the

partners.

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2 Conditions and basics of measurement concept

2.1 Summary of EN 15378

The standard “EN 15378 - Inspection of boilers and heating systems” specifies method for deter-mination of boiler efficiency and boiler seasonal efficiency. Annex D and E of this standard contains the description of the procedure in detail.

The method applied in this standard is based on indirect boiler efficiency determination principal. This means that all possible waste items are measured or estimated. Boiler efficiency and seasonal boiler efficiency can be gained taking onto account all these losses.

Main losses are followings: Flue gas heat loss Unburnt combustibles (CO, HC, soot) Boiler surface heat loss Standby loss – losses through the chimney with burner off

For determination of above mentioned losses following parameters should have been measured in the

same point, preferably with a multifunction device (combined probe), using an instrument complying

with EN 50379:

• θfl flue gas temperature (°C)

• O2 fl,dry oxygen dry flue gas contents (%)

• CO flue gas contents (ppm)

• Bacharach test

• θair combustion air temperature (°C) shall be measured at the burner intake.

• HUMair combustion air relative humidity. Assume 50% if not measured

• HUMfl flue gas relative humidity. Assume 100% if not measured

• Boiler surface temperature (°C)

This method is dealing with the boiler itself. It does not take too much attention to installation and operational circumstances. Some installation and operational condition slightly modify the efficiency calculated by this standard, but has significant effect on actual seasonal heating efficiency and reduce or increase actual fuel consumption.

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2.2 Basics of applied measurement concept

Measurement concept is going to apply in BOILEFF is based on direct boiler and seasonal effi-ciency determination method. Direct means measurement and comparison of useful energy with energy content of consumed fuel and auxiliary energy.

For this purpose following quantities shall be measured and stored for investigated period or season:

Fuel consumption

Electrical (auxiliary) energy consumption

Useful heat supply by heating and by hot water supply side.

Seasonal efficiency can be determined from these data:

yElectricitFiring

HotWaterHeatingseasonal QQ

QQ&&

&&

+

+=η

Advantage of this process that all major and minor effect is taken into account in this efficiency. From the viewpoint of Guaranteed Performance Quality (GPQU) it is the best way to apply. Disadvantage of this method, that it has not got any information about the distribution among waste items and can not be given any advice how to reduce wastes and improve further the efficiency. When someone is not satisfied with the efficiency waste measurement has to be performed according to the previous chapter.

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3 Measurement concept in detail

3.1 Dependence from firing system

Boilers and heat generation systems can have quite different firing, flue gas removal and combus-tion air supply systems. Three basic type in case of gas firing:

Open combustion system takes combustion air from the installation room and lead out flue gas by chimney.

Closed combustion system is sealed from installation room, takes combustion air from outside and lead out flue gas preferably on the same way

Condensing combustion system is similar to the closed system, but it is made to utilize con-densation heat of flue gas

This type of categorization can also be performed according to similar way at other fuel types as well. Figures of different firing system principals in case of combined wall-hung type boilers can be seen on Fig.1.

Fig 1.

Open Closed Condensing type Combustion system [1]

Fortunately applied direct method does not depend on the combustion system. The same meas-urement concept can be applied at any combustion system case.

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3.2 Fuel consumption measurement

3.2.1 Natural gas

Natural gas is supplied via pipeline network supply system. Invoicing happens by means of actu-

ally consumed quantity. For this purpose a gas-meter is installed into each consumer. This gas-meter

is also suitable for our purpose. But generally these gas meters do not have data collection system, so

the owner has to register the state of the counter regularly. Some small problem can be in that case

when natural gas is also used for cooking and in general gas consumption measured together with the

consumption of other systems. In this case an assessment can be made according to the following

table, which is also applied in EN 15378.

Table 1.

Sample values for cooking

3.2.2 LPG

LPG is used at lot of places where natural gas pipeline network supply system is not available.

LPG, which is propane or mixture of propane and butane, is stored in tank in liquid form. After natural

or forced vaporization LPG is fed to the local gas supply system of the building. In this case invoicing

happens by means of delivery, which is performed by tank lorries. So generally there is not any gas

meter installed in between storage tank and the boiler. In this case similar gas-meter is suggested to

apply and install as it is applied in case of natural gas.

3.2.3 Fuel oil

Fuel oil is also stored in storage tank. Fuel oil is fed by means of oil-pump to the local oil supply

system of the building. In this case invoicing happens by means of delivery, which is performed by

tank lorries. So generally there is not any oil-meter installed in between storage tank and the boiler. In

this case an oil meter is suggested to apply and install.

3.2.4 Solid fuel

Solid fuel fired systems, which means generally wood or wood-pellet as renewable energy re-

source, on one hand does not belongs to the scope of the project, as agreed by all the partners. On

the other hand it would be difficult to perform exact measurement because of uncertainty of heating

value because of humidity content variation of the fuel.

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3.3 Useful heat measurement

Useful heat can be measured by appropriate heat meters. Heat meter means a flow meter com-

bined with two temperature sensor. Available compact heat meters generally fitted with all facilities

and have calculation program inside and some storage capacity for collected data. In general hot

water generation is connected not directly to the boiler, but to the heating system. In this case boiler

inlet and outlet line is enough to measure. In this case one heat meter is enough, as can be seen on

Fig.2. Installation place selection has to be close to the inlet and outlet junction of the boiler.

Fig.2.

Heat meter installation in case of separated hot water tank connection

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In a lot of cases boiler can not be separated from hot water generation as it can be seen on Fig 1. and

Fig 3. , which shows wall hung type boilers with one through type HW generation and on Fig.3. which

shows integrated HW tank application. For these type of systems two heat meter installation will be

necessary, one for the heating system and one for the hot water supply system.

Fig. 3. Integrated Hot Water tank to the boiler [1]

In heating circle flow sensor has to be installed onto the heating return line and other temperature

sensor to the outgoing line. Colder water in return line gives more exact measurement condition to

flow measurement in most of the measurement solutions. In hot water side flow meter needs to be

installed onto the cold water line. Consumed water can be measured only in this line in case of circula-

tion pump application. Another temperature sensor shall be fit to the hot water line. This installation

can be seen on Fig.4.

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Fig.4.

Heat meter installation when hot water generation can not be separated

In case of application of hydraulic separator or buffer storage tank heat meter shall be installed before

these appliances, as it can be seen on Fig.5.

Fig.5.

Heat meter installation in case of hydraulic separator or buffer storage tank

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3.4 Measurement of electricity consumption

Electrical energy consumption is need to measure, because this gives useful information about

hydraulic balance and circulation pump operation. Furthermore other auxiliary equipments as combus-

tion air fans, control systems also consume a certain amount of electricity. This measurement can be

performed by means of electrical energy meters that can be installed into electrical sockets. In that

case when boiler has direct connection, electrical socket connection has to be installed. Fig.6. shows

an example for these types of meters.

Fig.6. Electrical energy meter example

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3.5 Specification of equipments

The aim was to investigate boilers having power from 10 kW up to 70 kW. But most of the cases

applied boilers power is less than 28 kW. Because of this reason meters can be separated

to smaller (< 28 kW) and to larger (< 70 kW) power rate when it seems to be necessary.

3.5.1 Fuel meter Natural gas: Existing fuel meter is used

LPG: Gas meter to low pressure gas side

Operational pressure: 25 mbar

Gas flow: max. 3 m3/h

Light fuel oil: Flow meter for fuel oil

Maximal flow: 3 l/h for small power

7 l/h for large power

Temperature range: 5 – 30 °C

3.5.2 Heat meter Fluid flow in the heating system depends on one hand the power and on the other hand on the

temperature difference (Δt) between outgoing and return line. Heat meter needs to fit to these condi-

tions. Maximal flow of heating water in different cases:

Maximal power: 28 kW 70 kW

Δt Fluid flow

10°C 2.5 m3/h 6.3 m3/h

15°C 1.6 m3/h 4.0 m3/h

20°C 1.3 m3/h 3.1 m3/h

For hot water side for maximal consumption two outflows is taken into account.

Maximal flow meter capacity for hot water supply: 1.5 m3/h

Maximal operational temperature: 90°C or higher

3.5.3 Electricity meter

Electrical energy meters that can be installed into electrical sockets.

Voltage: 220 – 240 V / AC

Max. amperage: min. 6 A or higher

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4 Meter installation terms, instructions to installers

4.1 Heat meter installation

Heat meter installation has to facilitate correct measurement of supplied useful heat quantity. Each circumstance which can distort the correct measurement has to be avoided.

Installation of heat meter has to be done according to installation instructions of the manufacturer. Installation position and flow direction has to be checked.

Each meter is sensitive to pollution in water. Filter has to be installed before the meter in line.

Each meter is sensitive to air bubbles in the water. It can distort measured quantity value. System deaeration has to be performed and automatic air-bleed valve has to be installed.

Back-flow via the heat meter can also distort the measurement. The best way to avoid back-flow is to install a non-return valve inline with the heat-meter.

4.2 Fuel meter installation

Fuel meter installation has to facilitate correct measurement of consumed fuel quantity. Each circum-stance which can distort the correct measurement has to be avoided.

Installation of fuel meter has to be done according to installation instructions of the manufacturer. Installation position and flow direction has to be checked.

In case fuel supply temperature and pressure is quite constant it is enough to calibrate the fuel meter.

In that case when temperature and pressure can fluctuate in wide range, pressure and temperature also needs to be measured and volume flow has to corrected using of these values.

4.3 Electricity meter installation

Electricity meter installation has to facilitate correct measurement of consumed electricity. Each cir-cumstance which can distort the correct measurement has to be avoided.

Installation of electricity meter has to be done according to installation instructions of the manufac-turer.

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5 References

[1] Figures are from public instruction materials of VAILLANT.

[2] EN 15378 - Inspection of boilers and heating systems

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Project partners:

The sole responsibility for the content of this report lies with the authors. It does not necessarily reflect the opinion of the European Communities. The European Commission is not responsible for any use that may be made of the information contained therein

BOILEFF Raising the efficiency of boiler installations · 2014. 8. 11. · BOILEFF Measurement...

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