Subject: Conference call with Portland Cement Association – Startups and Shutdowns 

Location: U.S. Environmental Protection Agency, Research Triangle Park, NC 

Date: November 2, 2011 

Participants: 

Portland Cement Association (PCA)

Andy O’Hare, PCA 

Curtis Leslie, Ash Grove 

Mike Pelan, Lafarge 

Hector Ybanez, Holcim 

U.S. Environmental Protection Agency (EPA)

Keith Barnett 

Sharon Nizich 

Peter Westlin 

RTI International

Mike Laney 

The purpose of the meeting was to discuss kiln and control device operations during startup and 

shutdown periods as they occur in the portland cement industry. The following key points were 

discussed: 

 Compliance requirements in the current portland cement NESHAP during startup and 

shutdown assume a cold startup following a prolonged shutdown typically for major 

maintenance and/or repairs. This type of startup would require several days involving the 

use of gas or oil fuels to bring the kiln temperature up to an optimum temperature at 

which feed materials would be re-introduced. According to industry, cold startups only 

occur one or two times in a year. 

 According to industry, most startups and shutdowns are associated with malfunctions or 

other unexpected, unplanned events. Startups from these events are considered warm

startups because the kiln typically is not shutdown completely but retains whatever load 

is in the kiln at the time of the malfunction or other event and the kiln continues to rotate, 

usually at a slower rate, and an alternate fuel is fired to maintain a temperature that will 

prevent the material in the kiln from cooling excessively. Completely shutting down the 

kiln (halting rotation and firing) while it retains a load of hot raw materials would warp 

the kiln. 

 Most startup and shutdown practices are safety driven. Complete shutdown with a cold 

start occurs just one or two times a year. The shutdown involves emptying as much of the 

load from the kiln as possible and bringing the kiln temperature down gradually to avoid 

damage to the kiln. These periods are used to perform major repairs and maintenance, 

such as replacing refractory bricks, on the kiln. Workers enter the kiln after it is cooled 

and use jack hammers to break up any solidified load. Cold starts must occur over several 

days in order to properly cure and seal refractory bricks. 
 During the more common shutdown to address a malfunction, the feed of raw materials 

to the kiln is suspended. The length of time the feed is suspended varies by kiln type and 

size. The longer wet kilns, for example, may require a longer shutdown and startup 

period than the shorter preheater/precalciner kilns. The length of the startup period will 

also depend on how the extent to which the kiln was shutdown. While the kiln is in a 

partial shutdown mode, no feed is being added, but the kiln continues to be kept warm by 

firing with an alternate fuel such as natural gas and the kiln rotation is slowed. 

 For economic and safety reasons and regardless of the type of shutdown, the goal in the 

industry is to return the kiln to full production as soon as possible. 

 Industry practice is to operate control devices anytime the kiln induced draft (ID) fan is 

operated. The ID fan is always on when fuel is being fired in the kiln. 

 Air flow through the kiln is lower during startup. 

 Kiln ID fans are typically variable speed, although some older kilns use constant speed 

fans and dampers to control air flow through the kiln. 

 A kiln is considered to be operating normally when it is producing quality clinker. 

 According to the industry, state Title V permits do not strictly define startup and 

shutdown, but typically leave it up to individual plants to determine when a startup and 

shutdown occurs. 

 The startup and shutdown of a kiln is more complicated than that of a boiler because of 

the presence of fuel and feed. A boiler startup and shutdown must only consider fuel. 

 For issues related to testing and monitoring during startup and shutdown, the industry has 

already provided information to the EPA.