Waupaca Foundry利用热交换技术的优势来降低废料/回收率并抵消砂添加剂的成本.

In foundry operations, 在制芯过程中，一致的砂温控制对于保持工艺成本至关重要, product bench life, and overall quality. 然而, that temperature consistency also can be the most difficult to achieve.

In most regions of the United States, 季节温度的波动会导致核心室进入的沙子温度上升70华氏度. 当送砂系统间歇运行时，这些温度变化会进一步放大, 或者在铸造过程中发生破坏，导致砂子过冷或过热.

In some cases, 已安装的工艺设备和相应的控制系统无法提供所需的温度控制. 没有这种控制会导致生产效率的降低、芯的报废、铸件的报废和返工.

“The foundry industry, traditionally, has never had very good temperature control for foundry sand,” said Mark Hoffman, Process Engineer/Project Manager with MT Systems Inc., 一家总部位于俄亥俄州的公司，作为系统集成商，在铸造行业有着深厚的根基, project manager and metalcasting equipment provider.

“The traditional way to heat foundry sand has been through calciner rod heaters, and when cooling, fluidized beds with cooling coils. 然而，线圈总是运行的方式热或方式冷比你想要你的出口温度是为了在短时间内调整沙子的温度.

“The problem is almost every foundry application is a start/stop run. You are not running sand at a continuous rate. And when you stop/start, you overheat the sand on the next run because the sand just sits there and gets hot. Or it gets too cold. So, you’re always left chasing your tail. People, for years, have never been happy with traditional heaters or coolers.”

Over the past six years, 世界上最大的独立铁铸造厂之一越来越多地采用间接垂直板技术，原因是在制芯过程中追求更一致的砂温控制.

When Waupaca Foundry, which operates three foundries in Waupaca, WI, started planning a new production line for Plant 3 in 2014, all options were on the table, recalled Adam Kurszewski, Plant 2/3 Assistant Production Manager – Coremaking.

Prior to 2014, Waupaca Foundry relied on those previously mentioned, traditional methods for cooling sand, before casting in the form of shell and tube exchangers. 然而,, Kurszewski noted those units were unable to handle increased capacity demands, 除了需要持续的维护和难以产生一致的砂温之外.

“In this case, 这是一个棕地开发项目，我们的核心房间安装了一条新生产线, including all the components. 寻找更好的选择来处理增加的产量和提供更精确的砂温控制也是有意义的. There were multiple reasons to pursue new technology,” he said.

Waupaca Foundry and its project partner MT Systems engaged Solex Thermal Science, a global leader in bulk solids heat exchange, to address its core-sand temperature control. 这家加拿大公司专门从事间接垂直板技术的应用，在50多个国家有600多个项目.

“我们的装置使工作流体与砂分离，并通过砂床间接传导热量. 这使得砂的混合温度非常精确和一致,” explained Scott Harris, Regional Director, Americas for Solex Thermal Science, 强调砂粒在中空不锈钢板之间的重力作用下均匀流动，而工作流体则与中空不锈钢板内的砂粒反向流动.

Temperature control — Harris将间接热交换器比作温度控制的砂调节系统，确保即使环境温度波动，岩心砂温度也可以集中在1°F内. 这大大改进了现有的技术，在现有的技术中，砂的温度变化可能高达20华氏度.

“In the Waupaca case, 我们发现我们真正喜欢这些热交换器的是你可以设定温度作为你想要的输出温度, and it matches your water temperature – plus or minus a couple of degrees,” Hoffman said. “You don’t fight it. You don’t overcompensate or under-compensate.

“There’s no response necessary to incoming sand temperature. If the incoming sand temperature changes from 80°F today to 60°F tomorrow, as long as we’ve properly adjusted the ranges of temperature of that sand coming in, the unit just takes care of everything. It offers the necessary retention time to handle that temperature fluctuation, 所以你不需要猜测一个操作设定值来得到你需要的温度.”

Installation considerations — Before entering the heat exchanger, the sand is transported via pressurized air to a receiver hopper, which feeds into the Solex inlet hopper. The hopper design may vary according to the selection of an air or bucket feed, restricted height, and enhanced inlet capacity that removes the need for a separate receiver hopper. For the Waupaca installation, pneumatic transporters deliver sand to a hopper mounted above the Solex exchanger.

在热交换器板前需要有足够体积的沙子，以保持沙子的恒定进料到热交换器, in the event of a supply disruption.  The capacity is typically designed to be 15 to 30 minutes of supply, depending on the foundry’s plant operational strategy.

In the Waupaca case, 热交换器外壳使用标准支撑支架安装在热交换器组的下方. 中间支撑是另一种选择，可以将热交换器悬挂在铸造厂上层.

出砂流量由MT系统控制的振动给料器控制, which meters out sand into the batch weigh hopper before it goes to the mixer. Knife gate feeders also are available.

工作流体的供应和控制需要根据目标温度和砂的期望流速来加热或冷却砂. Fluid modules and chiller and/or boiler systems can be added, depending on the facility auxiliary system resources available. In the Waupaca case, both hot and cold plant water is available.

在所有操作条件下保持加热或冷却模式下流体温度的系统控制也集成到设施控制方案中. Separate heat-exchanger fluid controls are an alternative option.

QC and cost advantages — With the new exchangers, 由于减少了岩心的报废和返工，Waupaca实现了几项重要的、显著的质量改进和成本降低. 由于砂粘合剂的优化使用，铸造废料和打捞也被最小化.

Kurszewski noted that since completing the Solex sand-conditioner installation, Waupaca铸造厂将模具/芯废品率降低了33%，抵消砂添加剂成本降低了10%.

“This is meaningful,” Hoffman explained. “You have to remember that when making a chemically bonded core or mold, sand is mixed with a small blend of ingredients that includes chemical binders – and, in some cases, also may include catalyst and dry additives. 在许多化学结合系统中，成分在从混合器排出到砂斗之前会开始一个化学反应硬化过程.”

他补充说，砂的温度对硬化过程的快慢起着重要的作用:这是混合砂在吹芯之前的工作寿命.

“If the sand is too hot or too cold, 配料的添加量(在暖箱工艺中是催化剂)需要调整, which can create inconsistencies in casting quality, as well as wasting of raw 材料. 然而,, if you combine a more accurate recipe with better temperature control, you’re going to have a more refined process and reduced scrap.”

Following the successful operation of the three Solex coolers at Waupaca’s Plant 3, three additional units were commissioned for Plant 3, one additional unit for Plant 1 also in Wisconsin, as well as four more at Waupaca Foundry’s Plant 5 in Tell City, IN.