CDR Pumps explains to MEPCA how, working in conjunction with Alcohols Ltd, a well renowned chemical solvents and hydrocarbons facility, on a large-scale project to provide a safe system for moving highly flammable solvents to VOC (Volatile organic compounds) directives.
The VOC system CDR Pumps has been working on originally included 17 single seal cast iron centrifugal pumps with a small re-circulation line from the discharge to the suction side of the unit. These units fed a flow meter which mechanically shut off when the required capacity of liquid had been pumped, forcing the solvent to flow through the smaller re-circulation line and, if left running, produced heat.
Previously an installation like this would have been perfectly adequate, but with improvements in chemical pump manufacturing, CDR Pumps had the potential to upgrade the system to a safer, more environmentally friendly installation with increased energy efficiency. However, whilst previously considered to be adequate, there were several issues with the original installation:
- Mechanical seal pumps are designed to leak, albeit parts per million, however, this still allows flammable vapours to escape enter the atmosphere
- Due to flow meter closing, the solvent passes through the re-circulation line and has the potential to produce heat energy
- Energy is wasted when the unit operates through the re-circulation line.
This set up produced excessive heat, wasted energy and with leaking vapours was not suitable for VOC applications and the latest ATEX legislation.
The challenge was to replace 17 pumps emitting a flammable vapour and excessive heat, whilst incorporating adequate pump protection.
The solution CDR Pumps presented to Alcohols Ltd was to upgrade to its magnetically driven centrifugal pumps, in conjunction with power monitors and Thermocouple protection. The pump manufacturer’s ETS 40 magnetically driven centrifugal pumps are perfect for this kind of application due to their seal-less design, featuring zero vapour loss. To protect mag drive pumps from dry running and operating against a closed valve, the company also incorporated a power monitor into the system. Power Monitors operate by monitoring the power consumption of the motor in relation to the required duty point of the system. If the pump is in a situation of running against a closed valve or dry running, the power monitor deactivates the pump within 0.2 seconds.
This protection device is set up with a new control philosophy complete with a new panel, emergency isolation switches and localized start/stop switches. For increased safety, the final device fitted was a PT100 Thermocouple; this constantly monitors heat generation internally within the pump. If the temperature rises above the set point (below the flash point of the solvent), the thermocouple will send a signal to the control panel and switch the specific pump off.
Replacing 17 existing pumps with new systems without impacting production may be a challenge, but it was achieved through a systematic strategy. This was despite the installation also including upgraded anti-static valves, pressure tested pipework and a whole new bespoke electrical panel, which was specifically designed and built with 17 power monitors intrinsically fitted.
The logistical aspects of this project needed to be organized in such a way so as not to impact production; downtime was not an option. Firstly CDR Pumps’ engineers fitted the new custom control panel alongside the old one. Pipework was pre-fabricated and pressure tested before the first batch of mechanical seal pumps were removed. The first four units were then removed alongside pipework and valves.
The first four mag drive pump systems were fitted alongside the pre-fabricated pipework, anti-static isolation valves and the PT 100 Thermocouples. Once the first stage was installed, tested and commissioned CDR Pumps continued installing all the pump systems, which were fitted and commissioned safely. Every individual pump system was tested to ensure the power monitors prevented the pumps from dry running and operating against a closed valve, and emergency isolators were fitted locally and tested on site.
The final install was extremely successful. Energy consumption has dropped significantly; accurate pump selection meant that motor powers could be reduced from 4kW to 2.2kW and in addition to smaller motors when the pumps are not required for operation (when the flow meter closes) the specific power monitor automatically shuts off the pump.
This set up is suitable for an ATEX Zone 1 area classification. All components were ATEX certified and supplied with certification with an individual tag number.
Replacing the old pumps with zero vapour loss mag drive pumps means hazardous vapours escaping into the environment were eradicated, producing a safer cleaner working environment. The installation also gave Alcohols Ltd piece of mind from knowing that it had a safe working system thanks to the two layers of pump protection. The first layer was a digital load monitor to prevent dry running, operating if a pipe splits and running against a closed valve, thereby preventing heat generation. The second safety device was the PT100 Thermocouple fitted to prevent excessive heat being produced with a flammable product.
CDR Pumps is proud that a system has now been put into place to prevent volatile organic chemical emissions escaping into the environment. All controls, valves, and pumps were executed to the highest ATEX standards and individually certified suitable for an ATEX Zone 1 area. Safety is of paramount importance, and with this in mind, the pump manufacturer has prevented the possibility of dry running, excessive heat being transmitted into a flammable product and sized the units to prevent static build-up. All 17 pump systems were specified to reduce energy consumption achieved by downgrading the motor sizes and automatic shut off.
