For a copper smelter in Poland, we designed and manufactured a custom shell-and-tube heat exchanger for use in a nickel(II) sulfate production plant. The unit heats a process medium containing sulfuric acid and metal compounds, using steam as the heating medium. The heat exchanger was developed as a replacement for the previously operated graphite unit.
A New Solution for a Demanding Chemical Process
Installations used in the metallurgical and chemical industries often operate with chemically aggressive media, elevated temperatures and variable process conditions. In such applications, a heat exchanger must provide not only the required thermal performance, but also process stability, structural tightness and safe operation.
In the installation described, the unit is used to heat a process medium containing sulfuric acid and metal compounds. Thermal energy is supplied by steam.
The project covered the entire implementation process: from developing the technical concept and selecting materials, through calculations and manufacturing, to testing, delivery and confirmation of the unit’s performance under actual operating conditions.
Technological Challenge
The heat exchanger was to be installed in an existing plant used in the nickel(II) sulfate production process. The unit had to be adapted both to the required thermal parameters and to the available space and existing connection arrangement.
The key project requirements included:
- operation with an acidic process medium containing metal compounds,
- stable heating of the process medium using steam,
- maintaining the required process temperature,
- the ability to operate under full vacuum conditions on the shell side,
- adaptation of the heat exchanger to the existing infrastructure,
- ensuring structural tightness and operational safety,
- delivery of the unit within a timeframe allowing installation during the plant’s scheduled maintenance shutdown.
An important part of the project was also the confirmation of the heat exchanger’s actual thermal performance after commissioning.
Individually Designed Shell-and-Tube Heat Exchanger
Hexonic designed a vertical shell-and-tube heat exchanger manufactured from grade 1.4571 stainless steel on both the tube side and the shell side. The material was selected to suit the parameters and operating conditions of this specific process installation.
The unit was designed to accommodate:
- the properties of the process medium,
- the required thermal duty,
- the available installation space,
- the existing process connections,
- vacuum operation on the shell side,
- transport and installation requirements.
Hexonic’s scope of supply included design engineering, thermal and hydraulic calculations, mechanical strength calculations, material selection, preparation of manufacturing documentation, production, quality control, required testing and delivery of the complete unit.
Heat Exchanger Technical Parameters
Unit type: Vertical shell-and-tube heat exchanger
Heat transfer area: 76.5 m²
Tube material: 1.4571
Shell material: 1.4571
Maximum allowable temperature: 180°C
Maximum allowable pressure: 10 bar
Shell-side vacuum conditions: Full vacuum down to –1 bar(g)
Process medium: Medium containing sulfuric acid and metal compounds
Heating medium: Steam
Empty weight: 5,360 kg
Operating weight when filled: 9,078 kg
Year of completion: 2026
Controlled Plant Start-Up
The start-up process began with filling the system with the process medium and gradually heating the equipment. Steam was then introduced into the heat exchanger.
During the initial stage, the steam flow rate was increased to approximately 3 Mg/h. Once stable operating conditions had been achieved, the flow rate was gradually increased to approximately 6 Mg/h. During this period, the temperature of the process medium rose from approximately 90°C to 120°C.
The results confirmed that the heat exchanger responded correctly to the increasing thermal load and was capable of achieving the required process temperature.
Guaranteed Performance Test
The actual guaranteed performance test was carried out continuously for 24 hours. During the test, the steam flow rate was maintained at approximately 6 Mg/h.
The temperature of the process medium downstream of the heat exchanger remained stable at between 118°C and 119.8°C. The required process temperature range was 116°C to 124°C.
Test Results
Continuous operating time: 24 hours
Steam flow rate: Approximately 6 Mg/h
Process medium outlet temperature: 118–119.8°C
Required temperature range: 116–124°C
Test result: Positive
Project Result
The test confirmed that the heat exchanger:
- meets the required thermal performance,
- ensures stable process temperature,
- can operate continuously at the required steam flow rate,
- provides an adequate thermal capacity margin,
- operates correctly with the existing process installation,
- meets the process parameters specified by the customer.
The positive test result confirmed that the individually designed shell-and-tube heat exchanger can effectively replace the previous solution used in this installation.
Heat Exchangers for Aggressive Process Media
Selecting a heat exchanger for a medium containing sulfuric acid requires an individual analysis of the chemical composition, concentration, temperature, pressure, flow rate and the presence of additional compounds or suspended solids.
Hexonic designs industrial heat exchangers tailored to the specific operating conditions of each installation. The implementation process may include application analysis, thermal and mechanical strength calculations, material selection, preparation of technical documentation, manufacturing, testing and confirmation of performance during commissioning.
What type of heat exchanger can be used for a medium containing sulfuric acid?
The heat exchanger type and construction material must be selected based on the acid concentration, temperature, pressure, flow rate and the presence of other chemical compounds. In the installation described, a custom-designed shell-and-tube heat exchanger made of grade 1.4571 stainless steel was used.
What heating medium was used in the heat exchanger?
- Steam is used as the heating medium. During the guaranteed performance test, the steam flow rate was approximately 6 Mg/h.
Can the heat exchanger operate under vacuum conditions?
Yes. The shell side of the heat exchanger was designed for operation under full vacuum conditions, down to –1 bar(g).
How was the unit’s thermal performance confirmed?
The thermal performance was confirmed during a continuous 24-hour test conducted under actual production conditions. The process medium temperature downstream of the heat exchanger remained within the required operating range.
Can a shell-and-tube heat exchanger replace a graphite heat exchanger?
In the application described, the shell-and-tube heat exchanger was designed as a replacement for the previously operated graphite unit. However, every such modernisation requires an individual analysis of the process conditions and material compatibility.
Do you need a heat exchanger for a demanding process?
Send us information about the medium, temperatures, flow rates, pressure and installation conditions. Based on these data, we will develop a solution tailored to the technological requirements and the existing installation.
