Area of Improvement:
Approx 5 TPH of condensate at 2.5 barg pressure was collected and transferred to boiler for condensate and heat recovery with the use of PPPU “Pressurized powered pumping unit”. A flash vessel was installed to collect flash generated though condensate at .5barg pressure and was utilized for hot water generation.
As the condensate was collected at 2.5 Kg/cm2(g) pressure and at 139 deg C temperature, flash of approx 250 Kg/hr was generated and used at hot water generation. 0.5barg Pressure was required at flash tank to transport it from flash tank to hot water generation system. Post flash recovery condensate of 110 deg C was being fed to pressurized powered pumping unit collection tank. PPPU condensate collection tank is of atmospheric pressure hence flash of about 90 Kg/hr was being vented to atmosphere as shown below.
Energy Conservation Measure:
Smoke like flash steam venting is not just loss of energy and water, but it also hamper aesthetic look of the plant. We have decided to recover flash like smoke like flash steam, but major concern was very low pressure of flash and issue with respect to the transportation of flash steam. So we decides not to flash condensate while transferring it to PPPU and operate PPPU at slightly higher pressure, We tested atmospheric tank for 2.5 barg Pressure, installed safety valve (may be avoided as it was already installed at flash seperator) and made arrangement for not reducing condensate line pressure at the PPPU collection tank. As we know during PPPU operation, after transfer stroke we need to vent out tank for next collection cycle hence vent line was also attached to flash tank as shown below.
As the motive steam pressure to the PPPU was 5 barg, No change was required to motive steam pressure. Payback in our case was below just 2 months, when steam was being generated with the use of coal.
As such no limitation, Safety aspects needs to be checked and followed before installation.