Introduction

Energy Management has become crucial to the competitors of the paper industry. Rising materia and fuel costs coupled with increased global competition is forcing paper mills to slash energy costs.Utility management therefore assumes significant importance in a paper mill.

There is tremendous potential to save energy of every kind in an average paper plant irrespective of its size. A 20% reduction in steam consumption for a 50 TPH plant saves USD 127000, equivalent to producing 150 tons of extra paper.

The  paper manufacturing process involves use of utilities like steam, compressed air, electrical power and large quantity of water to a varying degree depending upon the raw material used.  

Fuel savings in the Steam Generation Process Generation of steam or compressed air is at a central location and fuel/power savings can easily be effected by one or all the following steps:

• Flow Measurement of inputs/outputs with an Accuflo Flowmeter
• Combustion Control for Optimum Efficiency with an Effimax Package
• Heat Recovery from boiler blowdown using BHRU
• Effective cooling of compressed air at compressor outlet

• Use of steam traps on Digestor Preheaters
• Metering of steam to Deaerator
• Provision of Pumping Traps on evaporators
• Use of correct traps on radiator coils in Air heaters
• Use of special Sight Glasses (Spiraview)  on drying cylinders
• Use of System Unit on drying cylinders

Paper Machine Cascade System: Modern high-speed paper machines do not use conventional trapping methods for condensate removal. Ordinary sight glasses provided in cascading systems, fail frequently due to mechanical breakages and fogging of glass surface. Specially developed Spiraview glasses eliminate this problem with use of toughened glass, swirl chamber design and use of asbestos free gaskets.  

Condensate Recovery in the Paper Industry

Condensate available from the process is a high value source of energy savings as it has useful heat energy apart from being the ideal boiler feed water if returned to boiler. In a paper plant there are various areas of possible condensate contamination – Recovery Area being the major one – and the modern techniques provide means to check condensate quality on continuous basis. Use of Steam Driven Pressure Powered Pumps to handle condensate will enable returning it at higher temperature for better savings. Such pumps also save sizable electrical power used in motor driven pumps.  

Digestor Preheater

Considerable amount of steam is consumed in preheating black liquor circulated in chemical pulping. Lack of suitable steam traps and related accessories on condensate removal line allows large quantity of live steam to leak into condensate space. This not only results in loss of energy but also pressurizes condensate return lines creating water hammer conditions.Further, use of electrical pump to pump condensate back requires diluting this condensate with cooling water with loss of substantial thermal energy.

Condensate Purity Checks

Sampling of condensate coming out of individual preheaters rather than doing it near the condensate tank after collecting from all preheaters prevents potential loss from "good" preheaters whenever such contamination is detected. Condensate Contmination Detection System (CCDS) is the system designed to recover reusable condensate and drain the unwanted condensate.

Evaporator Condensate Drainage

Equipment usually working under vacuum conditions are difficult to drain as it calls for elaborate water seals to maintain the required vacuum. A steam driven condensate pump works as a pumping trap in such cases serving the function of both – a trap and a pump – to effectively drain out the condensate from evaporator bodies.

Next       Top