En­ergy ef­fi­ciency

DEMM Engineering & Manufacturing - - CONTENTS -

Ash­bur­ton Meat Processors is not only sav­ing more than $250,000 a year, it’s also done away with light fuel oil, which has halved its CO2 emis­sions thanks to heat pump tech­nol­ogy.

Re­cov­ered heat from re­frig­er­a­tion means Ash­bur­ton Meat Processors is get­ting more hot wa­ter than it needs, pro­duc­tion is more re­li­able and there’s am­ple room for fu­ture growth.

The firm, owned by Verk­erks, pro­cesses around 250,000 an­i­mals a year, equat­ing to 10,000 tonnes of meat prod­ucts.

Al­ready op­er­at­ing at the lim­its of what the plant could han­dle, the site needed to ex­pand in mid-2012, due to win­ning a ma­jor con­tract with Pork­corp NZ.

The ex­pan­sion was a per­fect op­por­tu­nity to re-think pro­duc­tion and ‘fu­ture proof’ the plant.

Sev­eral small re­frig­er­a­tion units were to be re­placed with an ef­fi­cient cen­tralised sys­tem – it was ideal tim­ing to re­visit the plant’s wa­ter heat­ing. With a fo­cus on en­vi­ron­men­tal per­for­mance, the firm opted for a new gen­er­a­tion high-tem­per­a­ture heat pump, thought to be the first in­stal­la­tion in New Zealand.

The heat pump uses ‘free en­ergy’ from re­frig­er­a­tion con­densers to gen­er­ate 70°C hot wa­ter – much hot­ter than is achiev­able with stan­dard heat re­cov­ery sys­tems on re­frig­er­a­tion.

With the ad­di­tion of a small LPG burner, the heat pump has re­placed the light fuel oil boiler, cut­ting CO2 emis­sions by 1,160 tonnes a year. All told, the project has cut en­ergy use by 27 per cent, worth $235,000 a year.

Pre­vi­ously, the re­frig­er­a­tion units across the site were in­ef­fi­cient and ex­pen­sive to main­tain. The new, cen­tralised am­mo­nia-gly­col sys­tem has re­duced en­ergy use by 424 MWh a year, sav­ing $ 63,800. It’s also elim­i­nated the need to use costly (and soon to be banned) Freon.

With age­ing pipes and con­stant vi­bra­tion, Freon leaks had been com­mon, and weren’t al­ways de­tected un­til plant failed – and find­ing the source could be tricky. The new sys­tem has less pipe work, , fewer valves, bet­ter mon­i­tor­ing and bet­ter con­trol than the units it re­placed.

It’s not only less prone to leaks, it’s eas­ier to spot them thanks to the gly­col used. The com­pany es­ti­mates its main­te­nance sav­ings at $20,000 per year.

Al­though there’s a per­cep­tion that am­mo­nia is less safe than Freon, the am­mo­nia is only within a closed-loop sys­tem in the con­trol room, with gly­col run­ning out to the plant.

The meat-pro­cess­ing firm is typ­i­cal of most in­dus­tri­alscale re­frig­er­a­tion sys­tems. With a large amount of re­frig­er­a­tion, comes a large amount of heat to dump – which is usu­ally done via a cool­ing tower or evap­o­ra­tive con­denser.

Stan­dard heat re­cov­ery sys­tems can re­cover 35-45°C wa­ter for use in the plant, but that’s not ter­ri­bly use­ful as most pro­cesses need wa­ter at much hot­ter tem­per­a­tures.

By con­trast, the high tem­per­a­ture heat pump uses ‘free en­ergy’ from the con­dens­ing sec­tion of the re­frig­er­a­tion sys­tem, as the evap­o­rat­ing sec­tion of the heat pump. This re­cov­ers all the heat and uses it to gen­er­ate 70°C hot wa­ter – far more use­ful, as it needs only a small en­ergy boost to reach the nec­es­sary 90°C.

En­ergy sav­ings from the heat pump are cal­cu­lated at 1,544 MWh a year, worth $171,200.

Hot wa­ter gen­er­a­tion from a heat pump has al­ways been tech­ni­cally fea­si­ble, but this is the first ap­pli­ca­tion of its kind in New Zealand that we’re aware of.

The firm is now in­stalling tanks to store hot wa­ter overnight, and max­imise its en­ergy sav­ings. This should save a fur­ther $ 60,000 in en­ergy a year – on top of the $235,000 al­ready saved.

Dave Gra­ham, op­er­a­tions man­ager at the firm says: “This project solved all our ca­pac­ity is­sues. Be­fore we were run­ning at the limit of our re­frig­er­a­tion plant and we were strug­gling to get enough hot wa­ter. Now we have an abun­dance of both chill­ing and hot wa­ter. We even have room for fu­ture ex­pan­sion.

“The high tem­per­a­ture heat pump is a po­ten­tial game changer for New Zealand Inc. Hot wa­ter gen­er­a­tion from a heat pump has al­ways been tech­ni­cally fea­si­ble, but this is the first ap­pli­ca­tion of its kind in New Zealand that we’re aware of.

“If we’re se­ri­ous about mov­ing away from coal and other fos­sil fu­els, then this is the tech­nol­ogy that we need. It’s re­li­able and proven. You can have con­fi­dence that it will work well and make sig­nif­i­cant cost sav­ings.”

Some of the new plant in­stalled by Ac­tive Re­frig­er­a­tion that’s help­ing the Ash­bur­ton Meat Pro­cess­ing firm save money.

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