Eliminate Condensate Bottlenecks in Reboiler Discharge
Reboilers using an inlet steam control valve arrangement (ISC) can provide significant economics and control benefits to certain distillation tower and stripping column installations. By exposing the full surface area of a reboiler to steam for effective heat transfer, the steam pressure can be lowered - which can reduce fouling that can occur with higher pressure steam and the corrosion that can occur with flooding a tube bundle. Control can improve because steam can adjust to process control demand changes much more rapidly than by the alternative of varying a liquid level - such as occurs with outlet condensate control (OCC). Furthermore, it is generally not possible to lose the condensate seal/reboiler duty when the proper drainage design is implemented. Other potential benefits include mitigation of the stratification that can plague channel head gasket in horizontal designs, and the use of “long” low pressure steam to improve the steam balance or reduce generation requirements.
In order to achieve those benefits, ISC systems need to overcome certain operational pitfalls / bottlenecks that hinder process operation. To help improve reboiler performance when using ISC operation, this presentation reviews historical negative experiences and provides design insight into mitigation options.
JAMES R. RISKO, CEM, PEM, MBA is president of TLV Corporation, Charlotte, NC, responsible for US and Canadian operations. He has 44 years’ steam systems experience, authored more than 60 technical articles, provided webinars to over 2,500 attendees globally, and presented at IETC, AIChE, Kister Distillation Symposium, RefComm, Distillation Experts Conclave, eChemExpo, and AFPM conference. He co-invented the world’s first combination pump-traps and created the “Extended Stall Chart,” for draining stalled heat exchangers. He is active in FCI, ANSI, and ISO standards. An avid tennis player, he has three energy management certifications.