Introduction Stripped Off Gas Evaporation 1 Evaporation 2 and Evaporation 3 Evaporation 4

120 © 2013 Published by Center for Pulp and Paper through REPTech2012 “Developing, Implementing and Maintaining an Energy Eficiency” in APRIL Indonesia Dady Iman Suhadi a , S.P. Manoharan b a Dady Iman Suhadi, Pkl.. Kerinci, 28300, Riau-Indonesia, dadyaprilasia.com b S.P. Manoharan, Pkl. Kerinci, 28300, Riau-Indonesia, SP-Manoharanaprilasia.com ABSTRACT APRIL Indonesia in Kabupaten Pelalawan - Riau Province is one of the companies under RGE Group involved in the manufacture of pulp paper with a capacity of 2.8 million adts year pulp and 0.8 million tons year paper. 88.5 of the energy required for the operation comes from biomass black liquor, bark and nearby palm industry waste products. Remaining 5.5 energy is met with Natural Gas and the balance 6.0 through Fossil fuel. Overall power requirement is sourced from its own power generating units and runs without any support of grid power. Power requirement of nearby township is also included in the operation. April Indonesia to conserve energy and reduce fossil fuel usage is always looking for other renewable energy sources new energy eficient methods of operation. Some projects under taken within the framework of energy eficiency include: 1 Methanol recovery from Stripped off gas SOG from Evaporator plant to substitute Heavy Fuel Oil and Natural Gas at Lime Kiln. 2 Bio-sludge of efluent treatment plant is processed along with black liquor to generate additional energy in recovery boiler. 3 Use of alternative organic fuels like palm shell, empty fruit bunch, palm fruit ibre etc. reduced fossil fuel usage.Energy eficient operation is continuously monitored and the speciic consumption of power, steam and water per adt of pulp and paper is in line with the best practices of the world. Keywords: energy eficiency, fuel, sludge

1. Introduction Stripped Off Gas

In the sulphate process, many different kinds of contaminants such as methanol and sulphur containing gases, TRS, are formed during the process. The foul condensate is processed in the stripper where most contaminations are removed as Stripper Off Gases SOG. In APRIL Indonesia Kerinci pulp mill condensate is cleaned in four strippers, one in each evaporation line 4 unit evaporator

1. Evaporation 1

In evaporation no.1 contaminated condensate foul condensate is pumped to a pre-heater where it is heated and the stripped from the stripper is cooled. Hot contaminated condensate is then feed to the stripper. Most of the steam from the stripper is condensed in a heat exchanger where black liquor is used as cooling media. Stripper gas from heat exchanger is piped to cooler using warm water as cooling media. Condensate from the condensers is feed as relux to top of the stripper. Stripped off gas is piped to methanol plant 1.

2. Evaporation 2 and Evaporation 3

The stripper system is evaporation no 2 and no 3 consist of one pre-heater in which the condensate to the stripper is heated and the cleaned condensate from stripper is cooled. The steam to the stripper is produced in a re-boiler where low pressure steam is condensed. Live steam condensate from re-boiler is piped to a lash tank where the condensates lashed off some steam to stage no 2 and stage no 3 in evaporation line. Low pressure steam is produced in a steam generator where most of the steam from the stripper is condensed. Condensate from the lash tank is pumped to the steam generator where it is evaporated. Stripped gas from the steam generator is piped to a trim condenser in order to adjust the concentration of methanol in SOG SOG is piped to methanol plant 1. Warm water is heated in the trim condenser. Condensate from the steam generator and trim condenser is pumped as relux to top of the stripper.

3. Evaporation 4

Contaminated condensate is pumped through a pre-heater to the stripper. In the pre-heater the contaminated condensate is heated and cleaned condensate is cooled. Steam from effect 1 is used as stripped steam. Steam from the stripper is piped to effect no 2 where most of the steam is condensed. Stripper gas from effect no 2 is lead to a trim condenser where the concentration is adjusted by cooling with warm water. The condensate from effect no 2 and the trim condenser is piped to a pump tank and then pumped to the top of the stripper as relux. Stripped off gas from stripper trim condenser is piped to methanol plant 2. Stripper off gas from evaporation 1, 2, 3 arepiped to Methanol plant 1 and evaporation 4 is piped to Methanol plant 2. ISBN : 978-602-17761-0-0 121 © 2013 Published by Center for Pulp and Paper through REPTech2012 Methanol Plant The gases that are taken out from the stripper contain amount of contaminants. The methanol system: • Stripped off Gas SOG is processed in the methanol column to receive combustible methanol, CNCG and condensate. • The methanol column is required to facilitate the separation and destruction of the contaminants formed in the sulphate pulp mill. • CNCG is separated from the methanol and sent to combustion • Methanol is collected in the methanol tank before sent to combustion. The methanol after the methanol system contains less than 20 w water and also different amount of TRS gases. The methanol and the TRS gases are normally taken to the lime kiln, recovery boiler or power boiler. • Methanol plant equipment: • Methanol column • Partial condenser • Final condenser • Methanol tank • Condensate pump • Methanol pump Technical data Methanol plant in Kerinci pulp mill - APRIL Indonesia 2 unit as Table 1. Sludge Handling Press Sludge and Bio-sludge Press Sludge Mixed Sludge: Sludge originating from different process of the plant was combined in a sludge mixing tank i.e. primary sludge and secondary sludge. The mixed sludge is pumped to six lines sludge dewatering, where water is separated from sludge by rotary screen thickener and screw press with helping chemical PAC Polymer. The dewatered sludge will be transferred and mixed with bark then ired in power boiler. The iltrate water is pumped back to the equalization basin. There are 6 unit screw press with total capacity 264 BDTday. 38 BDTday is 2 unit, 47 BDT day is 4 unit. Sludge feed consistency to rotary screen is 2 and 15 as outlet of rotary screen then feed to screw press and outlet consistency become 30. Bio-sludge: Sludge generated in activated sludge process collected and process through centrifuge with helping chemical Polymer. Sludge mixed with black liquor and ired in recovery boiler through evaporator processing. Detail of bio-sludge handling as follow: • Separation of bio-sludge by centrifuge • Inlet consistency centrifuge 2 and outlet consistency 16 • TSS iltrate 500 mgl • Sludge burning in recovery boiler through evaporator • Capacity 92 TPD 4 unit, 23 TPD Objective The objective of implementation methanol plant is utilization stripped off gas in methanol plant which usually is burned directly in boiler or incinerator but after methanol plant is provided so stripped off gas is processed to separate methanol with low water content then use as fuel source of energy in kiln or boiler. The objective of implementation sludge from efluent treatment iring in power boiler press sludge and sludge iring in recovery boiler bio-sludge is utilize solid waste as source of energy and reducing solid waste. Methodology Proven technology is available for methanol recovery. Visited other plants where this technology is already working. Discussed with customers irst and Table 1. Technical data Methanol plant in Kerinci pulp mill - APRIL Indonesia 2 unit No. Parameter Unit Value 1 Supplier Metso Power AB Sweden 2 No. of plants 2 Unit Per unit Total 3 Methanol Production Tday 32.4 64.8 4 Concentration 80.0 80.0 5 Caloric Value of Methanol kcalkg 4500 - 4800 4500 - 4800 122 © 2013 Published by Center for Pulp and Paper through REPTech2012 got irst hand information of any issues and results were encouraging. Contacted the supplier Metso Sweden and gave the green signal for the project. Result Discussion Methanol plant project was started in March 2010 and methanol can be produced in August 2010. The bio-sludge system was started in 2007. The production of methanol and sludge can be shown as Table 2 and Table 3.

5. Conclusion