案例6：加氢脱硫（HDS）和进料混合控制-1

带回家的消息
当遇到斜坡CVs时，CV优先级的概念和它的正确实施是非常重要的。用户以这种方式指定斜坡CV的优先级时必须小心，对每个应用基础如果遇到竞争的控制目标和/或残缺模式时，确保控制行为仍是需要的行为。对稳定斜坡CVs，在通过设定优先级完全相同将它们指定为同样重要的情况下，由于稳态约束的存在，斜坡CV对可到达目标计算依旧有较强的贡献。

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**Take Home Message **
The CV priority concept and its correct implementation when it comes to ramp CVs is extremely important. The user must take care in specifying ramp CV priorities in such a way that if either competing control objectives and/or crippled mode are encountered then the control behavior will be the desired behavior on a per application basis. In the cases where stable and ramp CVs are specified to be of the same importance by setting their Priorities identical the ramp CV will still have a stronger contribution to the reachable target calculation due to the stabilization constraint.

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案例6：加氢脱硫（HDS）和进料混合控制
(\Program Files\ShellGlobalSolutions\PCTP\Tutorial\SMOCPro\Tutorial6_HDSandFeed.wsp)
接下来我们提出了一个加氢脱硫（HDS）控制方案的例子。这里主要有两个目的：
1.为了说明子控制器的概念；
2.为了说明如何使用混合（多个）子控制器
过程模型
该过程描述由下图总结。

Figure 1 - HDS with pre-blender. 图1 -带预混器的HDS。

汽油的Sulphur（硫分）、T95和Density（密度）都从HDS反应器下游测量。问题是要将这些指标控制在各自的特定高限下面。操作变量是Kero（煤油），LGO和HGO的混合比，整体的进料流量和炉出口温度。
我们也将进料或利润范围最大化（优化）设定为经济函数。CGO比率的影响被建模并用作进料前馈干扰。
模型搭建
我们的目标是使用此策略搭建并调谐一个SMOCPro控制器。如下所示，在图形化模型构造器(GMB)中展现了过程模型。

传递功能块右上角的红色三角形表示Kero, LGO,HGO,CGO的比例增益是可以修改的。这一特性允许处理不同的进料类型。
从图中我们容易分别描绘混合加氢脱硫（HDS）反应器的子单元。因此我们使用此模型来说明子系统的概念。我们的意向是建立两个子系统，即一个用于搅拌器，另一个用于HDS反应器。“SULPHUR_IN”和“Dyn_SulfInToSulf”对应于子系统间的连接。
若要开始此流程，首先选择与搅拌器子模型相关联的所有块。选择完成后，在某一选中的块上右键鼠标按钮并选择Create SubSystem（创建子系统）。

选中的块被一可重命名为“BLENDER”的子系统块所代替。类似地，可在剩余的视图块创建“HDS”子系统（适当地重命名后）。

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原文：
**Case 6: Hydro-desulphurization (HDS) and Feed Blending Control **
(\Program Files\ShellGlobalSolutions\PCTP\Tutorial\SMOCPro\Tutorial6_HDSandFeed.wsp)
Next we present an example of a Hydro-Desulphurization (HDS) control scheme. Here, there are two main objectives:

1. To demonstrate the sub-controller concept
2. To demonstrate the use of blending (multiple) sub-controllers

**Process Model **
The process description is summarized by the figure below.
The gasoil Sulphur, T95 and Density are measured downstream from the HDS reactor. The problem is to control these qualities below their specific high limits. The manipulated variables are the Kero, LGO and HGO feed blending ratios, the overall Feed flow and the furnace outlet Temperature.
There is also a scope for Feed or Profit maximization (optimization) to be set as an economic function. The influence of the CGO ratio is modeled and used as a feed forward disturbance.
Model Building
The objective is to build and tune a SMOCPro controller using this strategy. The model for this process appears in the Graphical Model Builder (GMB) window shown below.
The top right red triangle in the transfer function blocks indicates that the gains for Kero, LGO, HGO and CGO are ratios that can be modified. This characteristic allows for processing of different Feed types.
From the figure, it is easy to delineate the blending and the HDS reactor sub-units, respectively. Thus, we use this model to illustrate the sub-system concept. The intent is to create two sub-systems, i.e. one for the blender and the other for the HDS reactor. The “SULPHUR_IN” to “Dyn_SulfInToSulf” corresponds to the link between the sub-systems.
To begin the process, first select all the blocks associated with the blender sub-model. After the selection has been done, right click the mouse button on one of the selected blocks and select Create SubSystem.
The selected blocks are replaced by a sub-system block that can be renamed “BLENDER”. Similarly, an “HDS” sub-system (after appropriately renaming it) can be created with the remaining blocks of the view.

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2016.6.9