Focus on - alfacombustion.comalfacombustion.com/data/documents/RX_VP0084UK01_english.pdf · riello...

Focus on

RX SeriesPremix Gas Burners

2

RX Series

INTRODUCTION p. 3

PREMIX TECHNOLOGY p. 4

RIELLO BURNERS RX SERIES p. 6

- COMBUSTION HEAD p. 7

- BURNER OPERATION p. 9

- PRODUCT ADVANTAGES AT A GLANCE p. 10

APPLICATIONS p. 11

- FOOD INDUSTRY p. 12

- HEATING p. 14

- INTEGRATION WITH RENEWABLE ENERGY p. 18

- PROCESS INDUSTRY p. 19

RX SERIES MODELS p. 20

Index

�

Riello Burners, world-wide leader in the production and commercialisation of burners, has been designing and manufacturing for almost 90 years, with vanguard technologies aimed to continuous innovation.Across the years, Riello Burners has gained the position of absolute leader in the world of residential, commercial and industrial burners, using technologies aimed to reduce consumption and caring for the environment. Now Riello Burners offers a complete series of burners, integrally designed on the basis of revolutionary Premix technology.The premix gas burner is the technological frontier, able to satisfy the requirements of high modulating turn down ratios and low polluting emissions, representing the ideal answer for the condensing applications and industrial processes.

Introduction

4

RX Series

Premix Technology

The main differences between a traditional pressure jet burner and a premix burner are in the ways in which air-gas combustion mixture is realized and in the technology of the combustion head. In pressure jet burners the gas and the combustion air are mixed at the end of the combustion head through special devices: the fl ame is located at the outlet of combustion head with diffusion in the space available in the combustion chamber.

The volume of the fl ame depends on the power output.

In premix burners the air-fuel mixture is upstream of the combustion head and can be obtained in different ways. In the smaller output ranges, the gas and air is delivered into the fan simultaneously and the mixing occurs inside the aspiration circuit. It is obviously necessary to use an airtight ventilation structure to avoid air-gas leaks.

The mixture fl ows subsequently inside the combustion head and through precision ports and exits to the external side of combustion head where ignition occurs and so the fl ame is established.The fl ame develops only on the external surface of the combustion head and so its dimension is practically the same as the combustion head itself.

Traditional fl ame air-gas mixture example

5

With larger output models, the gas is introduced downstream to the fan and so mixed before arriving in to the combustion head.In this case a sealed ventilation structure is not necessary because the gas and air mixture does not take place inside the aspiration circuit.

Premix air-gas mixing example with airtight aspiration circuit

Premix mixture and fl ame example with not airtight aspiration circuit

6

RX Series

Riello Burners RX gas burner series, completely designed and developed by Riello Burners for premix combustion technology, is the best answer to low polluting emissions and it allows to achieve high modulating turn down ratios.On models with outputs up to 250 kW the mixing of gas and air takes place within the aspiration circuit of the burner, ensuring a perfect air-gas mixture delivered to the combustion head and achieving low pollution emissions and high combustion effi ciency.An exclusive Riello Burners designed “Brushless” motor controls the fan speed and gas proportional valves and provides a perfect power output control.The combustion head is distinguished by a patented special “seamless knitted wire” which is produced through the use of a new technology. The manufacturing without a welded seam helps to avoid problems concerning thermal stress. The effi cient air-gas mixing and control from the fan speed along with the special metallic fi bre of the combustion head provides high turn down ratios (typically 7:1).The RX series burner operation can be “two stages progressive” or alternatively “modulating”. They are available with or without the burner cover, in standard or airtight confi guration and allow a highly fl exible confi guration depending on the application. In particular, the electronic control represents an open and versatile system.

Riello Burners RX Series

ASYNCRONOUS MOTORBRUSHLESS MOTOR

7

The combustion head of RX series has been uniquely designed by Riello Burners and represents the best solution for premix combustion.It is made with a metallic cylinder with multiple gas ports on the surface. A seamless knitted wire “sock” without welded seams covers the cylinder.

The air-gas mixture is delivered inside the combustion head, called also support. Through the ports, this mixture moves to the external side of the combustion head where ignition occurs through spark generation to an electrode.The geometry of the gas ports has been designed specifi cally to ensure that throughout the modulation range the speed of the air/gas mixture is higher than the one of a return fl ame, thus avoiding any potentially dangerous conditions.

The metallic sock is specifi cally designed and manufactured using a special alloy built with elements that optimise the resistance to thermal stress. It is the fundamental element of a premix burner that improves the performance and longevity of the combustion head.

Combustion Head

Seamless knitted wire detailCombustion head support with sock made in seamless knitted wire

Minimum modulation Maximum modulation

The seamless knitted wire is manufactured into a unique patented “sock”, that allows its application around the support without any welded seams. Thus critical situations to components caused from thermal stress, are eliminated.

The application of the metallic sock results in many advantages and improved performance:- The distribution of the gas/air mixture is complete without any other device, for example, double concentric cylinder. In this case the

elements, subject to different temperatures, could fail. - The fl ame developed on the surface of the combustion head is perfectly attached to the support even at maximum output. Also the risk

to have a return of the fl ame (light back) at minimum output is also avoided.- Turn down ratio typically 7:1.- Turn down ratios are achieved without the need for complex combustion head adjustments.- Thermal exchange increasing for irradiation, in particularly at minimum power, where the fl ame tends to enter the metallic sock. This

is very important because during its life cycle a combustion device operates most of time at medium power (about 70% of maximum load).

Example of combustion (view from boiler inspection window)

8

RX Series

- Low pollution emissions, below the limits set by the European Norms.- High combustion intensity. The combustion head of RX burners can normally work with combustion intensity of 2,5 MW/m2 compared

to medium market values of about 1 MW/m2.

The premix fl ame, as described, has a very compact geometry because combustion takes place close to the metallic fi bre and support. This feature reduces the likelihood of any contact of the fl ame with the combustion chamber walls, preventing incorrect combustion and chamber hot spots or localised boiling phenomenon that can occur inside a boiler body

Comparison between diffused fl ame and premixed fl ame at the same power

Diffusedfl ame

Premixedfl ame

The compact shape of a premix fl ame allows for a reduction in dimensions of the combustion chamber, which can be specifi cally designed to take advantage of this feature.

Another advantage of premix combustion is the reduction of fl ame noise. Therefore the chimney noise is also reduced with advantages on comfort especially applicable for residential applications in built-up areas.

Many tests have been carried out, in collaboration with the “Material engineering” department of a prestigious university.Here some examples of the test performed:

- high intensity combustion;- high turn-down ratio;- high thermal stress;- matching with combustion chambers at high and medium

temperature.

So in reliability tests, the material resistance and manufacturing processes have been confi rmed.

The combustion head of RX 350-500-700 models have integrated the RRD (resonance reduction device) that reduces all the possible resonance phenomena. So this head can be matched to various combustion chambers and so to be very fl exible during matching activities.

Micro graphic analysis example for material integrity checking, during operation cycle

Analysis of combustion head after working cycle. Test conditions: - application on boiler - operation with modulation min/max 7-35 kW - CO2 regulation = 9%

9

The operation of the RX from 35 to 250 kW range is based on variable speed drive motor technology.The motor speed variation also controls the regulation of gas delivery.The proportional gas train, follows the ventilation circuit pressure and supplies the correct quantity of gas.Therefore the variable speed control also manages the burner power.The RX 35 model is available in one stage, two stage or modulating operation, while RX 70-250 models can operate as a two stage progressive or as a fully modulating burner.

The RX S/PV series burners electronic controls are designed with modular concept in order to offer a highly fl exible confi guration dependant on the application.

On request it is also possible to supply the burners with variable speed drive control.

The operational logic of RX 350 to 700 models is similar to those traditional forced draught burners, except for the air/gas mixing section and burner head combustion system.A servomotor drives the air damper regulation then depending on the air delivery and so the pressure detected in the ventilation circuit, the proportional gas train supplies the correct gas quantity.In this case the ventilation circuit controls the gas output.

The servomotor has been specially designed to manage the ignition input independently of the minimum and maximum power required by the application.

RX 350 to 700 models are also available for two-stage progressive operation. For modulating operation it is necessary to install a PID controller for (example RWF40).

Burner Operation

10

RX Series

Product Advantages at a Glance

As previously described, the Riello Burners RX series presents many advantages and many solutions.In the following list we have summarised the most important features:- reduced noise ventilation;- wide modulation range, without the need of a movable

combustion head mechanism;- very compact fl ame;- thermal exchange increasing from irradiation, particularly at

minimum output;- possibility to obtain high combustion intensity with reduced

combustion head dimensions;- reduced combustion noise to the chimney.

Here below, the main advantages of RX 35 to 250 models:- high electrical absorption effi ciency (70%) Brushless motor;- shock absorber mounting that assure a reduction of motor

vibrations;- gas train directly assembled inside the burner body;- gas-train pre-set within the factory (Specifi c OEMS);

…and the product plus of RX 350 to 700 models:- same fan structures of traditional forced draught burners;- patented device for air/gas mixing downstream to the fan

providing safe operation;- metallic fi bre sock without welded seams avoiding failure due to

thermal stress;- patented RRD (resonance reduction device) integrated inside

the combustion head.

Very Low NOx emissions: < 70 mg /kWhEmissions values are lower than the more restrictive European Standard limits.

Very Low NOISE emissions: < 30% vs equivalent Pressure Jet Burner Chimney noise reduction.Advantages on comfort especially for applications in built-up areas.The variable speed control allows low noise emissions in the burner installation room.

11

Riello Burners R&D department is able to support its Customers in defi ning their own products, with optimised solutions.

RX Premix gas burners are designed to satisfy different demands:

HVAC applications (Boilers, Air Heaters, Furnaces, Absorption Chillers).

Process applications (Bakery Ovens, Grain Dryers, Spray Paint Booths).

In this section we have collected some technical sheets of Premix burners developed for some customers for different applications:- Food industry - Heating, ventilation and air conditioning- Integration with renewable energy - Process industry.

Some applications examples:

Further versions for other applications can be developed upon request and evaluation of our R&D department.

Applications

Application on bakery oven

Application on 3-pass smoke tube condensing boiler in inox

Application on hot air generator (30 kW)

Application on painting booth

12

RX Series

RX 25 S/PV ON - OFF OR MODULATING PWM

Food Industry

Burner dimensions

Position of combustion heads in the tunnel

Application on tunnel oven

Name: RX 25 S/PV

Output: 4-25 kW

Operation: On/off - modulating - two stage

Fuel: Natural gas

Combustion head: Cylindrical (d = 50 mm); length >1 meter for each combustion unit

Control: On-off or modulating with 3 points step control

Gas valve: Located by the inlet of the fan class B+C

Approval: On the system

Application: Tunnel oven for food industry

Remark: Available with cover, comunication bus to manage more than one combustion unit

13

RX 28 S/PV ON-OFF

Burner dimensions

Combustion chamber dimensions

Version 120 V also available with components CSA marked.

Application on bakery oven

Name: RX 28 S/PV

Output: 6-35 kW

Operation: On-off 28 kW

Fuel: Natural gas - LPG

Combustion head: Cylindrical (d = 50 mm) fi bre manufactured from knitted metal fi bre

Control: On-off (trimmer to set the output)

Gas valve: Located by the inlet of the fan class B+B


Applications: Rotating type backery oven, boilers

Remark: Components positioned on vertical line, anti-vibration joint, fl ame inspection window on the fl ange

14

RX Series

RX 35 S/PV ON-OFF OR HIGH LOW

Heating

Burner dimensions

Air heater dimensions

Application on air heater of 30 kW

With Premix burner With pressure jet burner

Name: RX 35 S/PV

Output: 6-35 kW

Operation: On-off 30 kW or high-low 20-35 kW


Combustion head: Cilyndrical (d = 50 mm) with fi bre

Operation: On-off (trimmer to set the output); high-low (3 trimmer for start-min-max)

Gas valve: At the inlet by the fan class B+B or B+C


Application: Air heaters, on-off boilers

Remarks: Special design to reduce combustion chamber dimensions and to reduce noise emissions at the chimney

15

RX 70 S/PV MODULATING

Burner dimensions


Application on vertical stainless steel condensing boiler

Name: RX 70 S/PV

Output: 12-70 kW

Operation: Modulating


Combustion head: Cylindrical (d = 67 mm) with fi bre

Control: high/low or modulating with 3 points step control

Gas valve: At the inlet of the fan class B+B

Approval: EN 676

Applications: Backery ovens, condensing boilers, grain dryers, etc.

16

RX Series


Burner dimensions Combustion chamber dimensions

Application on modular condensing boiler (150 kW each unit)

Name: RX 150 S/PV

Output range: 25-145 kW



Combustion head: Cylindrical (d = 84 mm) with fi bre

Control: High-low or modulating with 3 points step control

Gas valve: By the oulet of the fan class B+C


Applications: Bakery ovens, condensing boiler, grain dryer, air heater, etc.

Remark: Designed to be fi tted on combustion chamber with negative pressure -available with cover (RX 180)

17


Burner dimensions


Application on 3-pass stainless steel condensing boiler

* Different combustion head lengths are available, according to process application requirements.

Name: RX 250 S/PV




Combustion head: Cylindrical d = 119 mm with fi bre

Control: High-low or modulating with 3 points step control 0-10 V, 0-20 mA

Gas valve: By the inlet of the fan class A+A

Approval: EN 676

Applications: Bakery ovens, condensing boiler, grain dryer, air heaters, spray paint booth

Remark: Designed to be fi tted on combustion chamber with negative pressure - available with cover

18

RX Series

RX 10 S/PV MODULATING FRONT FLAME

Integration with Renewable Energy

Burner dimensions Combustion chamber dimensions

Application on hot water storage solar sets

Name: RX 10 S/PV

Output : 4-10 kW


Fuel: Natural gas

Combustion head: Cylindric (d = 50 mm) with knitted metal fi bre


Gas valve: located by at the inlet of the fan class B+C

Approval: On the system (package)

Application: Developed for hot water storage stratifi ed tanks for solar sets; applicable also on ovens and boilers

Remarks: Special design to reduce combustionchamber dimensions and to reduce noiseemissions at the chimney

19

Combustion head protection dimensions *

* Application on spray paint booths

RX 350 S/P MODULATING


Application on spray paint boothApplicaton on spray paint booth: exchange channel internal view

Burner dimensions

* Different combustion head lengths are available, according to application requirements.

Process Industry

Name: RX 350 S/P


Type: Modulating

Combustion head: Cylindrical d = 144 mm with fi bre


Gas valve: By the outlet of the fan class A+A


Approval: EN 676

Applications: Bakery ovens, condensing boiler grain dryer, air heaters, spray paint booth

Remark: Designed to be fi tted on combustion chamber with negative pressure - available with cover

20

RX Series

RX Series Models

RX 35-70-90-120-150 S/PV

RX 180-250 S/PV

RX 350-500-700 S/P

Output Range: 5 - 150 kW

Operation: On-Off, High Low, Modulating

Modulation: Through Fan variable speed drive

Motor: Brushless

Air-Gas Mixing Position: Fan Inlet

Aesthetics: Without cover

Combustion Head: Customized Approval on the System and EN 676

Approval: On the system or EN 675

Output Range: up to 250 kW

Operation: On-Off, High Low, Modulating

Modulation: Through Fan variable speed drive

Motor: Brushless

Air-Gas Mixing Position: Fan Inlet

Aesthetics: With cover

Combustion Head: Standard, with customisation options

Approval: EN 676

Output Range: up to 730 kW

Operation: High Low Progressive, Modulating

Modulation: With Air Damper

Motor: Asyncronous

Air-Gas Mixing Position: Combustion Head Inlet

Aesthetics: With cover

Combustion Head: Standard

Approval: EN 676

21

Note

22

RX Series

24

RX Series

VP

0084

UK

01 -

11/

2008

RIELLO S.p.A.

Via Ing. Pilade Riello, 537045 Legnago (VR) ItalyTel. +39.0442.630111 - Fax +39.0442.21980www.rielloburners.com - [email protected]

Riello Burners is a brand of Riello Group.

Since the Company is constantly engaged in the production improvement, the aesthetic and dimensional features, the technical data, the equipment and the accessories can be changed.This document contains confi dential and proprietary information of RIELLO S.p.A. Unless authorised, this information shall not be divulged, nor duplicated in whole or in part.

Focus on - alfacombustion.comalfacombustion.com/data/documents/RX_VP0084UK01_english.pdf · riello...

Documents

Transcript of Focus on - alfacombustion.comalfacombustion.com/data/documents/RX_VP0084UK01_english.pdf · riello...