Publication

Optimisation of lignite beater wheel mills using modern gas flow measurements

20191128120253mpsnovember2019

A new digital time-of-flight-based cross-correlation technique, employing pairs of robust infrared sensors, enables hot recirculation gas flow into lignite beater wheel mills to be accurately measured, with significant potential benefits for mill control

Modern beater wheel mills are still lacking sufficient measurement in order to be controlled by their total instantaneous mass energy balance. Besides unreliable measurement of air flows into the mill the main obstacle is the unknown amount of hot recirculation gas from the boiler which is used to dry the lignite in the mill and at the same time keep the mill inert so that no explosion hazard can occur.

Cross correlation technique

The control state space in which a beater wheel mill is operated and which is defined mainly by the enthalpy flows in and out of the mill can change rather quickly if individual parameters such as the water content of the lignite is changing rapidly. In this instance the mill gas in- and output flows can undergo changes which are hard to control as the amount of heat into and out of the mill is not known.

Modern mill & fan instrumentation for cement plants in russian language

modern-mill-and-fan-instrumentation-ru

Introduction

The constribution describes the tasks of accurately measuring gas flow through a large grinding mill such as a vertical roller mill for the production of raw meal. Besides the pure mechanical layout of the mill special attention has been given in recent years to the material and gas flow managment through the mill. The main aspects for this motivation are the product quality itself but beyond that also the flat lined operation of the mill.

Dust or no dust?

The large concern with grinding certainly is the quality of the processed product i.e. its finess at the nominal maximum throughput of the mill.

A vertical roller mill has to fullfill three basic processes which act together for achieving the best final grinding results ...

Application of measuring gas flow in the downcomer

190912-down-with-the-flow

Introduction

For the proper operation of equipment in a cement plant, knowing the flow rate is essential. In the past, high temperature and particulate in the gas stream have prevented online gas flow measurement. But the PROMECON Air Flow System utilizes the particulate to measure the velocity of the gas stream. Since the first installation at a cement plant in 2001, the system has been installed in more than 75 plants worldwide. The direct measurement of dust-carrying gas flows has opened new ways to monitor, control, and optimize the cement making process.

Measurement Technology

The system applies the triboelectric principle. Electrical signals created by the dust particle clouds passing each of the upstream/downstream sensors are cross correlated and referenced by their time shift. With the time of flight between the two sensors and a fixed distance (usually 350 mm), the actual particle velocity is known. For small particles, zero particle slip is assumed. The digital system requires no calibration, imparts no pressure drop, and does not drift over time.

A measurement point requires the installation of a pair of sensors aligned parallel to the longitudinal axis of the pipe. Using the cross sectional area of the pipe, as well as the pressure and temperature of the stream, the volume and mass flow can be calculated. Note that the only real measurement is time and that the measurement itself is not affected by temperature or pressure conditions of the stream.

On-line measurement and control in PF pipework

190822-mps-artikel-august

The key to successful biomass conversion

The conversion of coal firing systems to biomass poses some serious challenges to the operators. Especially when conventional mills i.e. vertical spindle mills are used, the switch away from coal to biomass results in a radically different behavior of the whole firing system. The typically emerging problems are mill trips, mill fires, flame shoot backs with the associated thermal damage to burner tips or even complete burner plugging or meltdowns including fires in the transport lines.

The two major difficulties are as follows

At first the nature of the problems and how to deal with them differs radically from the ones with coal. So different answers are to be found.

Secondly, as the whole firing system from feeder inlet to burner outlet is a fluid-dynamic black box, it is hard to say where in that complex process the problems exactly start. They can emerge at different locations in the process any time.

In Scandinavia where biomass firing began as well as in the UK with the largest Biomass to energy operation in the world, but also in continental Europe, the experience with the conversion of coal firing assets to biomass is similar. Mills seem to run stable for some time, but then, without warning, instabilities occur which can trip the system or even cause more harmful damage. It can be said that coal as a solid fuel is far more benign as biomass.

As a consequence power stations have started to use modern online measurement and control systems to measure the two phase flow inside the PF piping in order to bring some light into the dark of these problems.

Beater Wheel Mill control

presentation-beater-wheel-mill-control-icci-2019

Introduction

Presented by PROMECONs CEO Mr. Conrads at the ICCI Conference in Istanbul, the publication describes a novel method measuring hot recirculation gas into a beater wheel mill and gives an outlook on the application of this measurement for the better control of the mill operation.

Novel methos using an optical signal

Beater wheel mills in lignite power stations usually have a flue gas recirculation duct which allows the use of hot flue gas to dry the lignite during the grinding process. The beater wheel itself is grinding element as well as mill fan at the same time. The speed of the wheel determines not only the crushing process of the lignite but also influences the gas flow through the mill. One of the operational issues of lignite mills is the correct control of the beater wheel rotational speed for which besides the feeder information and the airflows through the mill the recirculation flue gas flow into the mill is a process variable.

Modern mill & fan instrumentation for cement plants

worldcement-modern-mill-and-fan-instrumentation-publication-image

Introduction

The constribution describes the tasks of accurately measuring gas flow through a large grinding mill such as a vertical roller mill for the production of raw meal. Besides the pure mechanical layout of the mill special attention has been given in recent years to the material and gas flow managment through the mill. The main aspects for this motivation are the product quality itself but beyond that also the flat lined operation of the mill.

Dust or no dust?

The large concern with grinding certainly is the quality of the processed product i.e. its finess at the nominal maximum throughput of the mill.

A vertical roller mill has to fullfill three basic processes which act together for achieving the best final grinding results ...

McON Air zur Luft­mengen­messung in der Müll­verbrennungs­anlage Bonn

deckblatt-reference-bonn-300x352-2

Einleitung

(dt.) Der Einsatz von PROMECONs innovativer Messtechnik McON Air in der Luftmengen-Regelung in einer Müllverbrennungsanlage führt zu Reduktionen der Temperaturspreizung oberhalb des Rostes um fast 50% und damit zu einer deutlich optimierte Prozessführung.

Erfolgreiche Innbetriebsetzung in der MVA Bonn

Die Müllverwertungsanlage der Stadtwerke Bonn GmbH (SWB-Verwertung) wurde 1992 mit zwei Linien als thermische Verwertungsanlage in Betrieb genommen. Seit 2000 wird die Anlage mit drei Linien und einem Jahresdurchsatz von ca. 250.000 Tonnen Brennstoff betrieben.

Mit der erfolgreichen Inbetriebsetzung der innovativen Luftmesstechnik McON Air der PROMECON GmbH, welche die individuelle Regelung der Rost-Primärluft der Linie 3 der MVA Bonn unterstützt, ist eine deutliche und wegweisende Innovation für die Feuerführung an einer Müllverbrennungsanlage ausgeführt worden.

Peak Performance - latest technology for optimised operation of large scale mills

300x352

Introduction

The article describes the task of accurately measuring gas flow through a large pulverizer such as a raw mill. Besides the pure mechanical layout of a pulverizer special attention has been given in recent years on the material and gas flow management through a large scale mill. The main aspects for this motivation are the product quality itself but beyond that also the flat lined operation of the pulverizer.

Optimised Grinding

The largest concern with grinding certainly is the quality of the processed product i.e. its fineness distribution as well as the nominal maximum throughput of a pulverizer at which it can keep the guaranteed fineness values.

A mill has three basic processes which act together in order to achieve the final grinding result:

The mechanical grinding part: This process is connected to the grinding elements of the mill, the tires, the bowl (on a vertical spindle mill) or the grinding media in a tube mill. ...

Go with the Flow - efficient gas flow measurement in cement plants

Introduction

For the proper operation of equipment in a cement plant, knowing the flow rate is essential. In the past, high temperature and particulate in the gas stream have prevented online gas flow measurement. But the Promecon Air Flow System utilises the particulate to measure the velocity of the gas stream.

Measurement technology

The system utilises the triboelectric principle. Electrical signals created by (dust) particle clouds passing each of the upstream/downstream sensors are cross correlated and referenced by their time shift. The digital system requires no calibration, ...

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