Determination of steam quantities in a gas-fired boiler plant

  • Accurate and reliable measuring data for the distribution and calculation of thermal energy
  • Calibrated differential pressure flow solutions for flow measurement of HP/LP steam and condensate (to ISO 5167)
  • Complete scope of delivery with flow nozzles, orifice meter runs, DP and pressure transmitters, temperature sensors and flow computers
  • Everything from a single source: from consultation and engineering to manufacturing and integration

1. Background

In 2017, international energy supplier E.ON entered into a long-term partnership with Dow Benelux to build, own and operate a large gas-fired boiler plant for their biggest production site in Europe, located in Terneuzen, the Netherlands. At this site Dow produces chemical intermediates which are further processed for a variety of products in commercial and industrial businesses such as packaging, coatings and foams.

A new boiler plant was integrated by E.ON Power Plants Belgium into the existing steam distribution grid at the Dow Benelux site in Terneuzen. The boiler has dual-fuel capabilities and can be operated on all mixtures of natural gas, hydrogen of up to 45% and the by-product fuel gas of the naphtha crackers. The boiler plant and the necessary components were designed for extreme requirements on load gradients, steam pressure tolerance and plant availability.

2. Measurement requirements

In order to be able to distribute and determine the steam quantities produced and to measure the return flow of polished condensate, the plant had to be equipped with suitable measuring technology. It was to be capable of measuring over a large dynamic range with high accuracy. For heat and mass balancing, the energy supplier required the measurement technology to be highly accurate in service, long-term stable and designed in accordance with the ISO 5167 standard. This implied that all measuring sections needed to be traceably calibrated at high Reynolds numbers.

Medium HP steam LP steam Polished condensate
Volume flow 400 t/h 50 t/h 400 t/h
Rated pressure: 56 bar 10 bar 14 bar
Rated temperature: +395°C +300°C +100°C
Control cabinet with DP and pressure transmitter, temperature transmitter and flow computer from KROHNE

3. KROHNE solution

Having carefully considered different approaches to steam measurement, the plant operator opted for KROHNE’s differential pressure (DP) solution with an ISA 1932 nozzle. This was the most efficient choice in terms of accuracy and long-term stability. The DP flow measurement with nozzle was engineered in accordance with the ISO 5167 and ASME MFC-3M standards as per customer requirements.

KROHNE's scope of delivery for measurement of high-pressure (HP) steam, low-pressure (LP) steam and polished condensate included six calibrated ISA 1932 nozzles (3 for HP steam, 3 for LP steam) and three calibrated OPTIBAR MR 4300 orifice meter runs (for condensate). The primary elements were installed in combination with the OPTIBAR DP 7060 differential pressure transmitter (incl. 5-way manifolds), the OPTITEMP TRA-S34 temperature sensor (incl. OPTITEMP TT 33 R rail-mounted temperature transmitter), plus the OPTIBAR PM 5060 pressure transmitter (with 3-way manifolds). Energy management on this project required dedicated flow
computing to determine the quantity and financial value of the HP/LP steam export as well as the import of polished condensate. KROHNE therefore also provided a flow computer that calculates the energy of steam and condensate from the input variables flow rate, (differential) pressure and temperature.

 

4. Customer benefits

Using KROHNE’s integrated DP flow solutions, the operator benefits from reliable and accurate data for heat and mass balancing. Given that even a small error can amount to a large financial difference on such projects, the calibrated DP flow solutions turned out to offer the best OPEX for the operator as they are long-term stable and accurate over a wide dynamic range. With design in accordance with ISO 5167, the measured values of the DP flowmeters can be checked for plausibility during process operation. This ensures that the measuring devices still work accurately and reliably as per customer specification.

KROHNE, as the main instrument vendor (MIV) for this solution, provided the whole scope of delivery itself – from consulting, engineering, manufacture and testing to project management and integration of the measuring equipment in the operator's process control system.

5. Products used

ISA 1932 nozzle

Flow nozzle for DP flow measurement of steam to ISO 5167, ASME MFC-3M or ASME PTC 6
KROHNE_Produktportfolio

OPTIBAR MR 4300

Fully preassembled orifice meter run assembly

OPTIBAR DP 7060

High-performance differential pressure transmitter with integrated line pressure measurement

OPTIBAR PM 5060

Process pressure transmitter with metal diaphragm

OPTITEMP TRA-S34

Resistance (RTD) thermometer with threaded connection for installation in existing thermowells

OPTITEMP TT 33 R

Rail-mounted temperature transmitter with universal inputs and galvanic isolation