*Appendix A.2 Unit C*

All retrofit proposals for unit C reduces the load on HTR-C. The current process layout is shown in Figure A6.

**Figure A6.** Current process scheme for selected part of Unit C.

Appendix A.2.1 Retrofit Proposal 4A

In retrofit proposal 4A, the feed is heated by internal heat exchange with other process streams in the same process unit. The pre-heating is smaller than in retrofit proposal 4B and 4C, which leads to less fuel savings but also less need for new heat exchanger area. The proposal is shown in Figure A7.

**Figure A7.** Retrofit proposal 4A.

#### Appendix A.2.2 Retrofit Proposal 4B

In retrofit proposal 4B, the feed is pre-heated with LP steam. A large part of the year, excess LP steam is vented to the atmosphere. In the proposal, some of this excess LP steam is used. The feed is pre-heated more than in retrofit proposal 4A, which gives larger fuel savings but bigger area increase in existing heat exchangers. Retrofit proposal 4B is shown in Figure A8.

**Figure A8.** Retrofit proposal 4B.

#### Appendix A.2.3 Retrofit Proposal 4C

In retrofit proposal 4C, the feed is pre-heated with LP steam as in retrofit proposal 4B. The difference is that the piping is changed and the hot reactor effluent is split to two parallel streams. This gives a slightly smaller area increase compared to 4C, but requires more piping and likely a more complex control system. The proposal is shown in Figure A9.

**Figure A9.** Retrofit proposal 4C.
